How to be good at L4D2, in order of importance:
1. Crouch when you shoot (unless you're shooting while moving but generally speaking you shouldn't be). This increases your accuracy and also allows others to shoot over you (you should always crouch if others are shooting past you).
2. Stick together and keep moving. Which seems contradictory. You need to always be moving (because L4D2 is *really* a resource management game). If you are stationary you are consuming resources (bullets, health) without gaining anything. But you need to stay close together in case anyone gets specialed or swamped. Maintain line of sight with each other ideally.
3. Use right click to push zombies away when they're hitting you. Use this when reloading or when trying to move through a horde. New users under-use this a lot and it accounts for much of their dying.
edit: 3b. When you're stationary, crouched and shooting (during a horde or when clearing a room) you want as little of you exposed to danger as possible. So the best option is to be in a corner so you know you're not going to get approached from the back or sides. Back to a wall or behind low cover is next best (being behind low cover also prevents Smokers from pulling you far away from your team, so look for cover when you hear them). In short, when you're shooting, think about and try to minimise the angles you can be attacked from.
4. Similarly, if someone near you is specialed (Smokered, Huntered or Jockeyed), if you're close enough, use right click to push the special off them so it can be dealt with. Don't just shoot it, it'll take longer and they'll lose more health.
(You can also right-click-push to interrupt a Hunter's pounce. If you push it *just* as it's about to land on you it will be stumbled and you can easily kill it. This is hard to do though, it's just about learning the timing.)
5. Deal with special infected *quickly*. Normal zombies don't do much damage (below Expert difficulty at least) whereas specials can fuck over the entire team. Locate them and kill them when you hear them.
6. Don't try to get someone up if there are still zombies around. If someone's downed then they're not actually losing health but if you try to get them up while zombies slap you, *you will be losing health*, which is a net loss. Kill the zombies *then* get them up. (Obviously if there's not time for that then get them up and take the hit, but usually there's enough time to do it the smart way).
7. Think of health (and other resources too, but it matters more with health) as communal. Because it is. Don't waste medkits, save them for when they're needed and use them on whoever needs them the most. The more people you have alive and shooting the better chance you all stand.
8. Use throwables appropriately. Pipes are good for getting rid of smallish group of zombies (so that you can get someone up for example). Molotovs should be thrown into chokepoints where zombies are coming from during a horde. Biles are used to distract a horde so that you can run past them (super-useful for rolling hordes).
Don't waste throwables. Make sure every team member is carrying one.
9. Tanks:
Take your time and keep your distance. If they get *at all* close, stop shooting and get away from them. Only shoot at them when you're sure you're not going to be hit. When you are in a decent position, just shoot them as much as you can (and look out for their rock throws which will become very readable and easy to dodge). You want to bring the tank down as fast as possible, obviously, but it's better to take longer than get hit. Don't waste throwables on tanks; biles will just spawn a horde giving you two problems instead of one. Molotovs are *sometimes* useful because you can just set the tank on fire and then ignore it until it dies but it's a bit of a waste. Pipes are handy if there are zombies around getting in your way - throw the pipe and concentrate on the tank.
10. Witches:
Unless you're very confident that you can crown it, leave it the fuck alone and just go around it. If you *have* to deal with it (cos it's in the way) then everyone should get a good distance from it and all start shooting it simultaneously.
11. Some of the achievements are really fun to do. Guardin' Gnome, for example. Do them. They're fun.
EDITED: 17 Feb 2016 13:41 by X3N0PH0N