In this game you will take four characters to adventures in the world of Solasta.
this guide will help you to chose the best characters for a first run.
it is possible that there are overall better options, but they require more work.
This party allows you to have very potent casters with very strong melee offence, and have all options covered, item crafting, potion crafting, damage spells, defense spells, lots of healing and picking locks. just in these four characters without sacrificing anything.

It is crucial to have a good wizard in this game, so the first character we will create is a wizard:

race: elf- has darkvision, the most important character trait in this game.
ancestry: high elf (extra cantrip, int +1 and +2 dex)
class: wizard
background: sellsword (you can wear medium armor, as soon as you get half plate, get one, mages are squishy, this background reduce this weakness)
at level 2 choose "shock arcanist" subclass for those huge damage numbers.
at level 4 choose feat "Flawless Concentration" so your spells will not end when you take damage. this feat is must have for any caster.
at level 8 choose feat "Raise Shield" this will allow you to wear shield in your offhand. and empty hand in your main hand
as there are no good wizard weapons, you will not miss anything while having no staff or wand in your main hand, but a magical shield in your offhand will increase your survivability vastly.

wizards can also naturally create magic items via "arcana" proficiency.

Since we need someone to do the heals, and have a lot of useful spells the second character we will create is a cleric:

race dwarf - has darkvision, the most important character trait in this game.
ancestry- hill dwarf (+1 wisdom for clerics, +2 con and +1 hp/level for sturdiness)
class: cleric -> Deity: "Einar" for the battle domain
battle domain allows you not only to use martial weapons, but also allows you to cast spells while having weapon/shield in your hands. the extra spells in this domain are also amazing.
background: Academic- bonus "manacalon rosary" proficiency that will allow you to create magic items, and take the medicine skill to create healing potions.

at level 4 choose feat "Flawless Concentration" so your spells will not end when you take damage. his feat is must have for any caster.
at level 8 choose feat "Armor master" for extra Armor class, every point helps.

this cleric character is not only a good healer and buffer, but also a very good tank with decent damage.

The third character will be our burglar, someone who will disarm traps, open locks, and stab people with swords, but... it will not be a rogue.

race elf - has darkvision, the most important character trait in this game.
ancestry - sylvan elf (extra move to reach your enemy faster and +1 wisdom for ranger abilities)
class: Ranger , favored enemy: undead
background: lowlife, this will give you proficiency with lockpics.

at level 2 choose fighting style "two weapon style"
at level 3 choose archetype: "Shadow Tamer", the dark slayer ability adds you extra damage to most of the enemies in the game.
at level 4 choose feat " Ambidextrous" so you can use two longswords at the same time (or any non-finesse weapons)
at level 6 chose favored enemy "Elemental"
at level 8 choose feat "twin blade", this feat effectively increase your AC by 3

remember to use "hunters mark" on the biggest enemy
don't be tempted to go for archery style, stay with dual weapons, it is much stronger.

The last character is our brawler with a huge two hander for massive damage, that's right, its a paladin!

race half-elf -has darkvision, +2 to charisma the main paladin stat, and two more scores +1
class: Paladin
background: doesn't matter, you can take philosopher for herbalist kit.

at level 2 chose fighting style "Great weapon fighting"
at level 3 choose sacred oath "Oath of Tirmar", this grants you very good spells like shield, blind and slow, and also grant extra damage against soraks.
at level 4 choose feat "follow up strike" for extra attack per turn
at level 8 choose feat "Flawless Concentration" so your spells will not end when you take damage.

Each caster should have one light cantrip. (light or sparkle)
some of the most difficult enemies in the game have disadvantage in light, making the simple light cantrip very potent against them.

Try to get "Alliance" standing with the antiquarians factions as soon as possible, then buy "belt of giant strength- hill" for everyone except the wizard. (if there is no in the shop inventory, exit the city and come back, might need long rest though...)

"slippers of spider climbing" don't require attunement!

sell magical weapons that you will not use, no need to hoard magical weapons and armors.

save often.