Let's first discuss the S.P.E.C.I.A.L attributes that define your character. When allocating points, note that I assume you have chosen the Gifted trait, which gives you +1 to all attributes.

Strength - Used to determine carry weight, also needed to handle weapons. If you have less strength than required for a weapon, you will suffer a -20% penalty for each point.
Verdict - 5 is a balanced value, allowing you to handle most of the weapons you will be using. 6 is needed for Bozar, but you can afford the penalty until Power Armor raises your strength, at which point you will be able to handle all weapons.

Perception - Determines Sequence, which decides the order in which characters act in combat. Also affects accuracy at range. Used in some quests.
Verdict - Six is needed for many of your perks (and some quests), and 8 for Sniper. You could start out with that value instead, and it won't hurt you that much. You can use Mentats to boost it if you need it for a perk.

Endurace - Mainly, it determines your starting HP, and the amount you get per level. Since you can use any number of stimpacks from your inventory, you only need enough HP to survive a single turn in a hard encounter. That said, extra health doesn't hurt and can protect you when you get hit with an unlucky critical.
Verdict - Four is the amount recommneded by Per Jorner, but the guide is written without Killap's patch, which removed an exploit found in New Reno, which allowed you to gain a large amount of damage resistance. This made the extra HP irrelevant. But I do use the patch, and dislike relying on exploits, and so I recommend 8. It makes the early and mid-game more comfortable.

Charisma - The main purpose of this statistic is to determine how many party members you can take with you. That value is half of your Charisma, rounded down (5 means you can only take 2). It is also relevant is some dialogue, but nothing important enough that you would raise it.
Verdict - Six is the value that is most "balanced", in that it gets you past some quests, and lets you take 3 party members. You can lower it without too much issue, as only really 2 party member are truly worth it, and put the other points elsewhere (Luck, if you want to build Sniper).
Starting with 2 (just for Sulik) is completely fine.

Intelligence - Determines how many skill points you get each level. Also used in conversation sometimes.
Verdict - I recommend 9, as skill points are handly, and Intelligence is a universally useful stat in Fallout. Seven is just fine, however, if you don't care about the points, with only a handful of situations where 9 is needed, which means a single Mentat will do the trick.

Agility - Determinutes how many Action Points you get in combat. Also impacts your starting Armor Class.
Verdict - 10. All the way here. More Action Points means more actions per turn, means you are better in combat. Period. I would set this skill higher, if the game allowed.

Luck - A curious statistic. Mostly it determines your Critical Chance in combat. Also needed for the Sniper Perk to be good.
Verdict - 2. The only use of this stat is to take Better Criticals and eventually Sniper as perks, which will make you completely unstoppable in combat. This is not at all necessary, however, as you can defeat just about anything without it. If you do want to go for that build, set this to at least 6 (with the buff from NCR, you will get to 8, which will be plenty). The 4 points can come from Endurance, Charisma, or even Intelligence (don't go lower than 7 on IN). Even with 2 luck (4 after the increase from NCR), Sniper perk still does good work for you, if you want it.
If you are building a Hand-to-Hand character, then you will want 4, so you can raise it to 6 in NCR, to grab Better Criticals. More isn't needed because Slayer isn't affected by Luck.

When you create a character, you can choose up to 2 traits. These are like perks, except they have both a positive and a negative effect. The idea here is choose the ones that provide the most value. As such, the choices are pretty obvious.

Top Traits

Gifted - Gain +1 to all Attributes, but -10% to all skills, and gain 5 less skill points per level.
Easily the best trait. 7 extra stat points is insane, and the skill point loss is irrelevant. You only need to raise a handful of skills, and will start out with enough intelligence that this trait basically has no drawback. All of my builds assume you have this trait.

Fast Shot - Guns use 1-less Action point to fire, but you cannot make targetted shots (that includes unarmed and melee attacks).
Pretty amazing. It lets you get a lot of shots off. Targetting with guns is pretty awful until the lategame, and burst weapons are much more efficient for defeating enemies anyways. If you want to aim anyways, you could use Mutate to swap it out for something else (Like Finesse).

Decent Traits

Small Frame - You get less Carry Weight, but you gain 1 Agility.
Reasonable trait. The Carry Weight penalty is annoying, but you get your first companion soon, and then the car soon after, so carrying stuff is not a big deal. The extra stat point can always be handy. If you don't want Gifted, this could be a decent substitute.

One Hander - You are more accurate with one-handed weapons, less accurate with 2-handed ones.
This trait is good for an unarmed specialist, since Power Fist is considered a one-handed weapon. So you get a nice accuracy bonus at no cost, since you don't care for any two-handed weapons.

Good Natured - get -10% to all combat skills, but +15% to Doctor, First Aid, Speech, and Barter.
Basically a skill point boost. You will use, at most, two combat skills, one of which is tagged. You lose something like 15 skill points, but gain back 30 (Doctor and Speech boosts are useful, Barter and First Aid are meaningless). Neat, but ultimately too marginal to matter.

Whatever Traits

Sex Appeal - Members of opposite sex like you more, members of same sex like you less.
Only really does anything if you are female, since you deal with more males in the world. Even so, it's too marginal to matter.

Fast Metabolism - You lose your resistance to poison and radiation, but you recover HP faster.
Neither side of this trait makes any difference in the game. Poison and Radiation aren't an issue, and recovering more health is meaningless since you can just rest (or use stimpacks even).

Bloody Mess - You always see the most violent deaths.
Fun, but ultimately does nothing in terms of gameplay.

Chem Reliant - You get addicted more easily, but recover from it faster.
Chem Resistant - You are less likely to be addicted, but chems affect you for a shorter period of time.
Drugs are minor at best. If you get addicted, you will probably just reload anyways. No reason to waste traits here.

Trash Tier Traits

Kamikaze - You lose your innate Armor Class, but get a bonus to Sequence (you act sooner in combat)
With a starting Agility of 10, thats 10 armor class you are losing, so enemies will get +10% to hit you. That's a bad deal. The bonus to sequence is not nearly enough to justify this. Even if it guaranteed that you act first.

Heavy Handed - You get +4 melee damage, but all your criticals do less damage.
The extra damage helps a little bit early on if your are a HtH character, but as soon as you get a halfway decent weapon (Power Fist), it won't matter. Later on, you will want to do criticals so this trait will just reduce your damage for no reason.

Bruiser - You gain +2 Strength, but get -2 Action Points
Absolute trash. 2 Action points are worth 4 points in Agility. So you trade 4 Agility for 2 Strength. Do I need to say more?

Skilled - You gain +5 skill points per level, but get a perk every 4 levels, instead of 3.
We chose Gifted because the skill penalty did not matter. So obviously, a trait that does the opposite is a bad deal. Perks are very valuable. Skills are not. You are losing on average 2 perks, for maybe 120 skill points. Sadly, there is nothing to do with those skill points. Bad deal.

Jinxed - Every miss has a 50% chance to become a critical miss (applies to everyone).
I have personally never tried this. Seems like it might be good for fun run, though, just to see how silly it gets, but competent opponents tend not to miss you much, so it won't help you when you might most need it.

Finesse - +10% Critical Chance, but all attacks do less damage (according to Wiki, this applies a +30 Damage Resistance modifier to all attacks, meaning it gets worse the better armored the target is, or if using ammo with a +modifier to target DR).
This trait is utter trash until the late game, when targetted attacks become good. Early on, you are not skilled enough with weapons to target consistently, and even if you do, most weapons will only allow a single targetted shot (at 6 Action Points) which, if it misses will do so little damage, it might as well have missed. Even it if hits, it will not always be a kill. You could simply use burst mode on a machine gun to definitely kill a target without any silly penalties. This trait is meant to be used late game, when you have high accuracy, good weapons, and Bonus Rate of Fire. You will get it via Mutate, by exchanging it with another trait.
Or you could just take Fast Shot and get many more shots with Sniper.

Fallout 2 features a total of 18 skills. Sadly, most of these are utterly useless. It is clear that the game was not fully realized, as many of these skills have potential, but the content to support that was simply not added.

We get 3 Tagged skills, these are skills that increase at twice the rate other skills. As it so happens, the choice for which ones to take is very simple.

Primary Skills - Skills you will tag because they are good.

Small Guns - Easily the best skill in the game. Firearms become available early on, and remain useful throughout the game. The strongest weapon we will use is, indeed, in this category.
You might not want to raise it right away, since you can find a few Guns and Bullets magazines early on, and reading those first will save you a few skill points. Afterwards, you will want this around 120% to ensure the maximum 95% hit chance from any decent range (more if you intend to use targeted attacks).

Speech - Makes your life easier by causing NPCs to give you quests and tell you stuff. Can often be the sole solution to a quest, and is universally the most useful non-combat skill in Fallout 2 (arguably all of the old isometric fallouts). Get it to around 100% at your earliest convenience.

Lockpick - Lets you get past locked doors, which often have good loot behind them. Less important of a tag compared to Speech and Small Guns, since once you get a lockpick item, you cannot jam locks anymore. Still, it helps to get it up high early, and tagging it makes that happen. There aren't any other pressing skills to tag (even though tagging Big Guns instead could yield more skill points).

Unarmed - If you intend to be a HtH character, you will use this instead of Small guns. Better than Melee Weapons in my opinion.

Secondary Skills - Raise these after your Primary Skills

Big Guns - Bozar is an insanely powerful weapon that you will use to defeat the "heavy" enemies, like Super Mutants, Aliens, Floaters, and such. Tagging it is not necessary, since it takes time before you get the weapon. You shouldn't need more than 90-100%.

Doctor - You need it at 60% to get Living Anatomy, a useful perk, and eventually 75% to aquire the Combat Implants. Also useful to have to fix the occasional crippled limb.

Science - You will want this at 81% eventually for Myron's quests, which includes the ability for him to turn regular stimpacks into super stimpacks. Early on, read Science books to raise this, until you reach around 60-70% and books aren't providing much value anymore.

Other Skills - Ones you use, but do not need to spend any points on

Repair - Raise this with books. Sometimes needed for a quest, or to mess up forcefields.

First Aid - A worse version of Doctor. Raise with books, though to be honest you can just ignore this skill.

Outdoorsman - Helps you avoid encounters. You can raise this with books, but if Sulik is with you, his skill will be used instead, since he starts at 40%, and gets another 10 per level. You will get another +20 from a Motion Sensor (must be in your own inventory). I'd stick with Sulik and ignore this skill.

Useless Skills - Skills that do not help you in any meaningful way.

Melee Weapons - Unarmed is more useful if you want to play that way. Overall, guns are just better than HtH combat.

Energy Weapons - Not at all bad, but they are just not better than Small Guns. The mid-game is the only time where you can get an energy weapon that matters, specifically the Turbo Plasma Rifle. It has a better single-shot damage than any small gun outside of the Gauss weapons. But Gauss Rifle easily outclasses it, and for pure damage, you are better off with burst-fire weapons. Pulse Rifle only slightly edges out the Gauss weapons, but has less accuracy and range. At the end of the day, tagging and raising this skill does not offer much value compared to just sticking with Small Guns (and maybe a Bozar).

Traps - These do not come up very often, and aren't dangerous enough to kill you.

Throwing - Grenades are not powerful or plentiful enough to warrant using them in combat.

Sneak - Never necessary. Stealth simply isn't an aspect Fallout 2 has fleshed out.

Steal - Acquiring money and wealth is not difficult in Fallout 2. Even if you wanted to steal, you can just reload if you fail, negating the need to invest points.

Barter - Even with minimum skill and 2 charisma, you will still struggle to spend all the money you get from just looting enemies, making the skill pointless.

Gambling - You could use this to amass a large quantity of money in casinos if you raise it high enough, but you could just become rich from looting firearms from enemies.

Perks are an important part of your character. They are few, available very three levels (four, if you took Skilled, but hopefully didn't). As such, you can expect to get only 8-9 of these, so they must be chosen very well.

You want perks to make you better in combat. Extra mobility, more damage, and more actions are all critical bonuses you want. Fallout 2 has a wide array of absolutely garbage perks, that one should avoid like the plague.

I will not list all the perks, since that would be tedious. Instead, I will list the general perk progression that I follow, since it does not really vary across characters very much. Other perks will be put into broad categories.

Top Perks, ones you will be taking, and the level (requirements in parenthesis). Note that HtH characters will take different perks at lvl 15 and 24.

Level 3 - Awareness (Perception 5)
Very interesting perk. It allows you to see the exact HP and weapon that an enemy has, rather than the "Severly Wounded" message you normally get. Even for someone like me, who knows almost all stats of all enemies, this remains tremendously useful, since you cannot predict who you will run into in random encounters. This is the only perk that doesn't make you directly better in combat, but it is very worth it.

Level 6 - Bonus Move (Agility 5)
Grants you 2 extra Action Points, that can only be used for movement. Mobility is very useful in the game, so this perk is excellent. HtH characters will love it even more. Since you will want to use burst mode of your weapons up close, being able to get around faster is very good.

Level 9 - Bonus Move, second time (Agility 5)
That's 4 Action Points in total for movement. Trivializes most melee enemies, and is extremely useful for everyone.

ALTERNATIVELY-----------------
Level 9 - Better Criticals (Perception 6, Luck 6, Agility 4)
Causes critical hits to do +20% more damage, and allows you to cause Instant Death criticals as well. Strong if you are going for Sniper, or are playing a Melee Character.
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Level 12 - Living Anatomy (Doctor Skill at 60%)
Adds 5 damage to every attack against living targets, which is added after all other modifiers, including armor and critical multipliers. Which means that it will always add exactly 5 damage, even if the entire attack would do zero damage, or if you scored a massive criticals. It also gives +10% Doctor skill. The 5 extra damage is pretty nice thoughout the game, expecially when you make many attacks per turn. It only becomse somewhat obselete late game, when you will be causing criticals almost every turn. Until then, it is a great perk to boost your damage output, and lets you compete in the New Reno boxing without being good at unarmed.

Level 15 - Bonus Rate of Fire (Perception 6, Intelligence 6, Agility 7)
Makes all ranged attacks cost 1 less Action Point. Insane perk, it allows you to fire many more times, especially when combined Fast Shot. Late game, you can often attack up to six times. Automatic pick for all ranged characters.

Level 18 and 21 - Action Boy (Agility 5)
Grants one extra Action Point per rank, to use as you wish in combat. More actions per turn is always good, and with the second rank, you will get that 6th attack, or just be able to move further each turn. Great for any character.

Level 24 - Sniper (Perception 8, Agility 8, Small Guns Skill at 80%)
Gives a chance, equal to your Luck x10, to cause a critical hit with every shot. Completely insane, and with a good Luck score turns you into a god. Combined with Fast Shot and many attacks, you will be dishing out absurd amounts of damage. Once you get this perk, only Enclave and Navarro troops will pose any threat to you. This perk is the reason you start out with a decent luck score.
If you started with 2 Luck instead, it is a lot less good, since you will just have 4 luck total, but 40% crit chance is still pretty solid. If you don't want this perk, then consider one of the following:

Other perks that are decent, and you might want.

Bonus HtH Attacks (Agility 6) - Makes unarmed attacks (including unarmed weapons) cost 1 less Action Point. If you are playing a HtH character, take this instead of Bonus Rate of Fire.

Slayer (Agility 8, Strength 8, Unarmed Skill 80%) - Makes all your hand-to-hand attacks critical, regardless of Luck. If you are playing a HtH character, take this instead of Sniper.

Toughness (Endurance 6, Luck 6) - Grants +10% Damage Resistance (normal only). Might be reasonable if you go the HtH route for extra protection, and don't mind giving up Awareness.

Lifegiver (Endurance 4) - You gain +4 HP per level. Picking this will get you a lot of HP, but you could also just start with a higher Endurance. Too much HP becomes redundant, especially later.

Quick Pockets (Agility 5) - Makes using invetory cost only 2 Action Points, instead of 4. Convenient, but not super necessary.


Avoid any perks that give skill points, since extra skills are not useful. Here And Now, along with Swift Learner are especially terrible, since they help you gain more levels. But the purpose of gaining levels is to gain perks, not the other way around. Most other perks have effects that do not affect combat, and as such, are utterly useless.

The attributes and perks I recommended are for a firearm-oriented character. But you could also play as a HtH character for an extra challenge. Let's summerize our choices.

Ranged Character:

Traits - Fast Shot, Gifted

Strength - 5
Perception - 7
Endurance - 8 (Or less)
Charisma - 4 (May vary)
Intelligence - 9 (7, if you need more stats)
Agility - 10
Luck - 4 (Varies)

For Endurance, Luck, and Charisma, you can adjust values as you see fit. More Charisma means more party members, and more Luck means more powerful lategame. Higher Endurance makes early and midgame a bit more comfortable. You could lower Charisma to 2 if you don't want more than one party member (or none), and pump other stats, or even Intelligence.

Perks - Awareness, Bonus Move, Bonus Move(2) (Or Better Criticals), Living Anatomy, Bonus Rate of Fire, Action Boy, Action Boy, Sniper.
If you reach level 27, you can take another Bonus Move for extra mobility.

Weapon Progression: You start out with just your fists, along with a Spear. Unarmed has a higher base skill, so use punches and kicks to get past the Temple of Trials, and the rest of Arroyo.
In Klamath, you will find the Pipe Rifle in Vic's Shack, use that against rats and such, until you find the 10mm Pistol in the Rat Caves.
When you get to the Den, you can buy the 10mm Submachine gun, which will be your first burst weapon. It should kill most opponents at this point in one attack, though you might not have lots of ammo for it. The .44 Magnum Revolver is quite efficient for single shots, as it has a higher rate of fire and better damage per shot. Use it whenever you don't need to burst. FInally, the Hunting Rifle is useful when you need to fight at night, or just longer range in general.
When you are asked to go to NCR while in Vault City, you can buy the H&K P90c, which is effectively an upgraded 10mm Sub, with much better damage, and a better rate of fire. This weapon will serve you very well, and the single shot is reasonable enough to use as well, especially with Living Anatomy in place. The Sniper Rifle, found in Sierra Army Depot, will cover your long-range needs.
When you raid Toxic Caves, you will recover the mighty Bozar. Though it lacks single-shot, its burst will destory any opponent short of a Deathclaw or an Enclave soldier. Use it against some of the heavier opponents, like Mutants, Floaters, and such.
The Military Base is where you will find your final weapon, the Gauss Pistol. It has a higher rate of fire, and has excellent damage and range. With Bozar covering your burst-fire needs, the Gauss Pistol will decimate any smaller foes at range. With up to six shots per turn, you can kill several smaller opponents per turn.
When you aquire the Sniper perk, things get silly. Gauss Pistol will lay waste to anything that isn't an Enclave Trooper, and even those will go down in just a few shots. Bozar will kill pretty much anything outside of the Final Boss. You will rarely even have to use Bozar.

HtH Character: - Less effective than a ranged character, but if you are looking for a more challenging game, this is a good way to do so.

Traits - One-Hander, Gifted

Strength - 5
Perception - 7
Endurance - 8
Charisma - 6
Intelligence - 7
Agility - 10
Luck - 4

Not that much changes. You lower luck, because Slayer is not affected by it. You just need 6 for Better Criticals, so 4 is your starting value. You could even pump Endurance to 10 if you don't care much about party members, though as a HtH character, you might want the extra firepower.

Perks: Awareness (Toughness, if you don't care about the extra knowledge), Bonus Move, Better Criticals, Living Anatomy (Or Bonus Move rank 2 for extra mobility), Bonus HtH Attacks, Action Boy, Action Boy, Slayer.

Weapon Progression: Pretty brief this time, you start out with fists, and can get Spiked Knuckles in Klamath. After that, the Power Fist awaits in Broken Hills, which can be upgraded to Mega Power Fist in New Reno, and that is basically it. Your punches will always be less powerful than burst-fire weapons, and you lack the long range attacking ability that Gauss Pistol would provide.

Fallout 2 offers quite a few companions found throughout the game, ranging from regular humans and ghouls, to robots, supermutants, and even a Deathclaw. They can carry items for you, and help in combat, and some can even use skills outside of it. They tend to drop off in usefulness towards the end of the game, but by then, you will be powerful enough on your own to not need them.
Unlike you, they need 2 Action Point to use any stimpacks, so be sure to give them Super Stimpacks so maximize their effectiveness.

Companions level up with you, gaining a level here and there, until they reach their max. This means that companions found later have less of a chance to be useful, which encourages the player to prioritize the earlier ones.


TOP PICKS

Sulik - Found in Klamath, he will join you if you settle his debt.

Sulik is a powerhouse in the early game and remains quite useful throughout. Start him out with a Melee Weapon (Combat Knife or Sharpened Spear), then give him an SMG for better damage. The 10mm sub is a good start once you get a decent supply of 10mm Ammo. Upgrade him to H&K P90c, and eventually the H&K G11E. The .223 Pistol is a decent alternative if you don't want him to burst.
If he is bursting, his "Distance" setting should be "Charge", which will cause him to run right up to enemies before bursting, thus maximizing his damage. Also he should "Never" run away, so that he always tries healing instead of running (which might just get him killed).
He also has a decent Outdoorsman skill, meaning you don't have to bother raising your own.

Marcus - Found in Broken Hills, will join you once you do quests for him there.

Very strong throughout the mid-game, he has a lot of health and can use large weapons. You will want to take away his Minigun, otherwise he is likely to kill your party members. Give him a Turbo Plasma Rifle as soon as possible, then upgrade to Pulse Rifle. He has enough Action Points to fire twice, giving him excellent ranged DPS. His main weakness is that he cannot wear armor, which means he is vulnerable to end-game weapons. He will struggle to survive against Navarro and Enclave, or any powerful burst-fire opponents.
Also, his movement animations are slow.

These two guys are your main choices. They offer strong support from the moment you get them all the way until you don't need them anymore, when you have Gauss weapons and a Bozar.

DECENT PICKS

Skynet - Found in Sierra Army Depot, if you assemble a new body for it.
If you can get the Cybernetic Brain for it, it is actually a decent NPC. It Has 10 Action Points to start, meaning it can fire twice from the get-go. You will want to start it either with a Sniper Rifle (better range, but only one shot), or a .223 Pistol, which will let it shoot twice. Eventually it should be given the Gauss Rifle. It has very high HP but, like Marcus, it cannot wear Power Armor making it vulnerable in the endgame.
Has very slow animations.

Cassidy - Found in Vault City, will join you if you ask him.

Vic - Found in the Den, will join you if you buy him from the slavers (or kill them).

I am grouping these together, becuase they function very similarly.
They are both what you might called "basic rifleman". For most of the game, they are much weaker than Marcus or Sulik, since they only get a single shot with a rifle. They do pick up towards the end, when they can get two shots with a Gauss Rifle. Start them out with a Hunting Rifle, then upgrade to Sniper Rifle, then finally Gauss Rifle. The Red Raider BB Gun (The one that actually does damage) is also a good pick before Gauss Rifle.

Cassidy has a bit better stats overall, while Vic has the repair skill which can use on a few occasions outside of combat (like disabling force-fields). Vic has more total levels he goes through, but does end up with pretty good stats towards the end (especially his final level).

Myron - Found in the Stables, he will join you if you ask him.

Not useful in combat, but you will want to pick him up for the quest to find a cure for Jet, as well as his ability to turn regular Stimpacks into Super Stimpacks. Park him somewhere convenient when not needed.


OTHERS

All other companions go here. None of them are as good as the ones above, but if you want to try a different playthrough, then bringing a different suite of companions is one way to do that.

Davin, Miria - Found in Modoc, will follow you if you marry either of them. Neither can level up, and have very low HP, making them cannon fodder.
Dogmeat, Robodog, K-9 - They are dogs, meaning they don't carry items for you and are melee only.
Goris - a Deathclaw found in Vault 13. The animation of him taking his cloak on and off alone is reason enough to not bother with him. Melee companions are inevitably going to be worse than those who use guns, and Goris comes too late in the game to matter.
Lenny - Found in Gecko, he has a LOT of health, actually. But with only 7 Action Points, he doesn't output a lot of damage.