Well, I have a couple of tactics that I usually use as a survivor. First, I try to keep moving. If we waste time and sit back all that's going to happen is more zombies will spawn and we'll have more to worry about. Keep moving forward and things will be much easier. Second, close doors behind you. I know that sounds trivial but it really helps. It slows the infected down and keeps them from sneaking up on you. You know when a hunter is on the other side of the door when it starts breaking down, so when that happens just shoot out the door and try to kill it. Third, know when to go back for people and when to just leave them. If somebody set off the car alarm and has a hunter on them outside it may be best to just leave them. If you go out there to help them all that's going to happen is you'll get grabbed by a smoker, vomited on by a boomer, or both. Also, when running for the rescue vehicle, going back for an incapacitated teammate will do nothing but get you both killed. Leave him to his fate.
Now, as the infected, being successful is heavily dependent on everyone knowing their specific class's role on the team. The Boomer's job is to vomit on the survivors to create a panic, then the hunters and smokers have to capitalize on the panic the boomer has caused. As a boomer, make sure you sneak up on the survivors. If you run at them in the open they'll see you and shoot you before you can do any damage. Also, don't go suicidal every time. You can do much more damage if you vomit, hide, then vomit again. Remember, your group's success is heavily dependent on you. Don't disappoint. As a hunter, do not attack the survivors when they are all together in a group. You will just get killed quickly and then when your team actually needs you you'll be waiting to respawn. Also, do not steal kills from smokers. Instead, try to cover the smoker by pouncing on the survivor that comes to rescue the one the smoker has. As a smoker, remember that your job is to pull survivors places that they don't want to go. If the survivors are up high, try to pull them down low. If the fall is great enough that in itself will do damage. Finally, if you are the tank, let your teammates help you. It isn't all about you, so if you see that a hunter has pounced one of the survivors, just leave him alone and try to kill the others. Do not hit the survivor he has pounced, that will just knock him off and free the pinned survivor. Finally, do not try to kill an incapacitated survivor. All that will happen is he will chip away at your health enough so that you will be easily taken out by his teammates. Instead, once a survivor is down, try to incapacitate his friends. Remember, to win you don't have to kill all the survivors, just incapacitate them. I hope this was helpful.
