The xenomorph has 4 main friends: Stealth, Suprise, Speed and Manevurability. Stealth and suprise kind of go together and shouldn't need much explaining, but some important things should be noted. For starters, every little noise you make can be heard by everyone near you, and can give away your position to a trained set of ears. This is especially true for hissing. As a general rule, dont hiss at all in a combat situation. You give valuable information about your race and location you don't want your enemy to have when you hiss. Also, a great way to not die is to leap at your prey instead of rushing twards them. To do this, go into focus mode and left click when your target is highlighted. If you are high enough you can knock the victim down, making them easy (and tasty) prey. However, more experience players (especially marines) will block your attack, knocking YOU down for a short little bit. At that point unless a blue moon happpens and all the planets align you are far pasted ♥♥♥♥♥♥. Anouther thing, anywhere besides the ground tends to be your friend. It helps you hide, run away, surprise your foes, eveything a xeno could want. A final tip is to watch out for marines with shotguns. Think of it as a silverback gorrila with flamethrowers for arms: it's scary, very dangerous, and if not handled right YOUR WORST ♥♥♥♥♥♥♥ NIGHTMARE. The shotgun does unfathomable damage at close range AND has a high chance of knocking you down, even at longer ranges.

Here we shall discuss tactics to use against a paticular race. First, we shall start with the marine:
The marine is very good at taking down still, far away, or overly-agressive targets. They tend to group up and when they do the are hard to take down, or at least do so compleatly and without dieing. They do this because even the best of them have a big flaw: there health. Marines have horrible health, the lowest in the game actually. You can kill one in 3 light attacks, 2 heavy attacks, or 1 heavy 1 light attack ( note, even if you knock em down the leap still counts only as a light attack, however you do extra damage while the are down so any attack at all will kill them when they are down). Also, they tend to band together in one part of the map so kill them before they get there or just avoid that area. Really it's not hard just stay the ♥♥♥♥ away and it will help you as you wont be feeding them. Also a marine with a smartgun is a major priority. Think of the smartgun as a shotgun with better range and less skill to use. However, even in experienced hands it can't outshine the murderous potential of the shotgun. One final thing about marines: you got to keep in mind that they have a motion traker. They can detect your movements, but not when you're still.
Next we talk about anti-predator strategies:
The predator is kind of like a wierd-ass hybrid in terms if abilities between the marine and the xenomorph. They are pretty fast, fast as a xeno when sprinting, they even have the same stamina as a xeno. They can leap up to places like treebranches and pillars and can leap at foes like the xenomorph. They have a variety of weapons, from the unwieldly combi stick to the highly-cheap plazma mines. I say the mines are cheap because I can think of few ways to use them fairly. A lot of predators like to use them right as you chase them so your ass gets blown to hell before you have the chance to even touch them. A lot of them also use them to make it pratically impossable for a xenomorph to kill them (e.g. placing a ♥♥♥♥ ton of them around where they plazma snipe so when you try and kill them you get killed by 20 ♥♥♥♥♥♥♥ mines right where you stand). However, there is hope to defeat this ♥♥♥♥♥♥♥♥ menace. What you do is if you notice the mines just sprint and run right twards them. If you dont ♥♥♥♥ up your timeing on a major level you will set off the mine and get off unharmed. Another thing to watch out for is the bomberang. Predators like to spam it once they get good with it and with little to no skill can rack up loads of kills because in all ♥♥♥♥♥♥♥ honesty the predator as a whole is unbalanced. Just remember: open ground is where predators like to use various weapons that never seem to run out of energy to rape innocent xenomorphs everywhere and it is your duty to murder them.
Finally we get to anti-xenomorph tactics, but this is the hardest of all. Really, I dont have any unique tactics that can't also apply to some other race. Remember, if you can smell them they probably know your there too. When I say smell I mean that literally. The highlighted color around all living things, thats you smelling the horomones they release. Also, keep in mind that if you leap at a xeno on a wall or something it will knock them down, giving you a bit of time to get a heavy attack going.

Do: Try to stay in groups. It can help more than a little when fighting a swarm of humans and it doesn't hurt when fighting a lone foe to have a little help ya know.
Do: Distroy lights. I don't know about the rest of you but looking at an unbroken lightsorce pisses me off and it makes me feel good to rid the world of it. Call it xenomorph instincts but this isn't a problem but it's a good thing for one major reason: darkness is a xenomorph's friend. If they can't ♥♥♥♥♥♥♥ see you they won't kill you! It's that simple! However, predators have alien vision which highlights us no matter the light conditions, but it all gets ♥♥♥♥♥♥ up near light, so if you are quite sure they are using it go to a light source and commence the murder.
Do: Use your tail. No I know that when fighting on the ground you usually can't use your tail but on a wall or roof you always can. This is important because if your foe has his back to a wall you can run up to them and nail them in the head with your tail. This will take two shots to kill a marine or predator if you do it right.
Do: Switch it up! Now, a lot of you are wondering what do I mean by this, and what I mean is don't use the same tactics, especially on a underpopulated servers. For example, I usually like to take down marines by leaping directly at them and then murdering. However, especially against a good marine, I sometimes jump right infront of them, hit them with a heavy attack as they remain confused as to what the ♥♥♥♥ is going on and finish them off with a light attack.This can apply to any strategy against any race(s). However, it should be noted that if its really working it shouldn't be stoped. Now, a lot of you are probably thinking this can lead to some really cheap things going down, but heres the thing, as long as you don't do the cheap-ass ♥♥♥♥ I'm going to list in the Don't section there will be a difference between cheap and effective: something that is cheap is unfair and often has no counter besides knowing the exact thing that exact player will do in a situation to avoid getting kill in a really unfair manner, but with something thats effective there's a well known and well understod counter to what you are doing that gives your foe a good chance to fight back and even win.
Don't: Use your speed to be a ass. What I mean by saying this is don't just sprint behind an enemy when they see you and stealth kill them or pull that ♥♥♥♥ in the middle of a fight. Its ♥♥♥♥♥♥♥ ♥♥♥♥♥♥♥♥ and it makes you out to be an ass. Now, sometimes you do it by acident or pure instinct. Fine, thats ok. Even I sometimes do it. But if you knowingly do it a lot than thats when you become an ♥♥♥♥♥♥♥ and hopefully get reported. This applies to predators too. It doesn't matter your race if you pull ♥♥♥♥♥♥♥ ♥♥♥♥ like this your still an ass.
Don't: Use hacks. Really guys? The game already has a small community and it doesn't need this ♥♥♥♥. However, there is an exeption. If your useing hacks to make the game more enjoyable for EVERYBODY than thats cool, I have no qualms with that and I doubt anyone besides the most stuck-up pieces of ♥♥♥♥ will eather. But, if your useing hacks to ruin peoples games you will get reported, banned, an then you will be just ♥♥♥♥♥♥. So just don't do it.
Don't: Be a whiney ♥♥♥♥♥. Look, if you think something's unfair, call out whoever is doing it and explain why. However, this doesn't mean put caplocks on and insult the ♥♥♥♥ out of your foe, friend, whoever it is. Now sometimes you will have adequit reasons to do it, but just try to keep it to a minimum. We all get angry and thats ok, but expressing control can really help, both in the game and outside of it.

There are a few advanced tactics that you can try at home. I will list a few but if you know more please list them in the comments below.
1. The Fake-Out: This is when you basically sucker-punch your foe using deseption. What you do is you go into a heavy attack, but half way through you block. This will cancel out the heavy attack and block the light attack your foe will use to counter it, giving you a perfect oprotunity to knock em down and murder them.
2. The ♥♥♥♥-You-Too: This is when a predator sets up some mines in a more enclosed space, leaves, and you attract him by setting off the mines and waiting right outside the doorway (or wherever he will enter) and stealth killing them. Maybe this is a little cheap but thouse mother ♥♥♥♥♥♥♥ mines are so cheap that I feel its justified even if its cheap.
3. The Suprise:This is when your high up and a marine your about to leap to notices you. What you do is you just leap right behind them and heavy attack them. They will think your pouncing and block, giving you a perfect oprotunity to kill them.
4. The Tunnel Tecnique: What you do is when you are in a very enclosed space is you strike first with your tail, leap, and hit them once more with a light attack. This strategy was made for the sole purpose of killing marines and trying it on a predator wont work.
Note: These are all tactics you can do alone. In an organised group you can probably pull ♥♥♥♥ off to make even the best, most skilled players ♥♥♥♥ there pants with fear. However, it should also be noted xenomorphs tend to have a hard time sticking together due to there speed and nearly unlimited mobility. Plus, always remember, working with, well, any other living thing not trying to kill you means sometimes you kills will be stolen, so suck it up because I would bet a pretty penny you do it too. All the tactics here have been proven effective, but, at least in some of the bigger matches, if what your doing works than dont change it. The majority of these tactics are ment for smaller games against skilled players but use all this as you like I guess.

Thank you for reading. Add your own imput on what was said here in the comments and give me a like if you agree with what I said here. I may be updating this guide if I feel there's something I should put in here (e.g. more advanced tactics).