Are you tired of just looking in Player hosted matches and finding no one there?
Well it's the easiest thing to do that most "newbies" don't realise, all you have to do is...
Step 1: Click multiplayer (Obviously)
Step 2: Click "Browse"
Step 3: See that toggle to switch to "Player hosted, Dedicated (LAN) or Dedicated (Internet)"?
well click Dedicated (Internet)
Step 4: Click Browse again and watch as you see lots of servers!

and that's All you have to do!

You are an Xenomorph
And you are trying to survive the Humans AND Predators all you have to do is this...

Well stick to the walls and wait for a potential "prey" and dont use your tail at first otherwise it alerts them so make sure you are high up (Quite a bit) and Shift (Lock target) them and pounce them therefore knocks them down, then if you want to you could "E" them or Heavy attack them.
Also if you prefer to stay on the ground (like me) Dont sprint-charge them as they will likely block your attack so either try and be stealthy and go behind them or if they go to leap (For predators and Xenomorphs only as they are the only races that do this) you block their attack, stunning them for a few seconds and giving you a chance to light attack them. And remember, trying to destroy the lights can also help you in multiplayer as the predator and the marine can hardley see you (well the predator can if he/she has their alien vision on in which cases stick to the light). Also creeping will NOT stop you from being seen on a marines motion tracker so be wary!

Okay, so you're a Predator

You need to know how to survive the Alien and Marine
Firstly, you don't need all these cannons and such to survive against an Alien as they don't have ranged attacks either. However, a Marine is a different story.

Aliens
You need to know your opponent to realise if they're going to do a heavy or light attack.
Most people just go for light, light, heavy or heavy, light, light. So you need to know first of all there is no blocking a heavy attack but you can however, use a light attack to stop it and as that happens you have a short chance to kill them, but with a light attack going on a block will stun the opponent and therefore giving you the kill.
Also, make sure to keep your alien vision on more so if there are more aliens than anything and also do yourself a favour by looking at the ceiling too.

Marines
These can prove a handful if you don't pick the right weapons, it's best not to go into melee combat with a Marine as they can really only do ranged attacks so it's best you adapt to the situation.
Make sure you are cloaked so they cannot see you and try not to use a weapon with a laser if you prefer stealth kills so the Spear would be best.
Also, make sure that you have your heat vision on so you can see them quite clearly and compared to a Xenomorph they are quite weak but if you do not take care you will just get killed.

You're a Marine
I've got some bad news...This is probably the hardest to play as if you're just a noob at the game so BEWARE
The Marine is the only fully ranged attacker in the game therefore becoming harder to play as slightly but remember, all hope is not lost.
As a Marine you have granades, a gun and a motion tracker, you'd be suprised to know how much that motion tracker helps so keep it handy and use it.
Okay so firstly, you need to spare your granades for a large group of opponents and since you're the main target for the two opposing teams, you'll need them.
ALWAYS keep an eye on the ceiling as your motion tracker cant detect something that isn't moving so beware for that.
Keep your bullets until you have an accurate shot and dont go just firing everywhere otherwise...you're just wasting ammo.
NEVER stick to the walls as that actualy leaves you MORE vunerable to attack as you'll have nowhere to escape and you then become an easy target for an alien to either E grab you or tail kill you. Also, its best if you become more observant so you can see those cloaked predators and don't stay in an open area for too long otherwise you're practically a free kill waiting to happen.

I have not been playing this game for quite a while now and so this guide remains outdated. I can recommend you do have a read through though and if you see anything that could be improved on, please let me know! Thanks.