Left 4 Dead Basic Infected Tips

Hunter: This is the hardest infected to learn. But the best tip is that you only have to press LB once to get crouched. After that, you can RT to pounce as many times as you want without crouching again. If you fall off a building however, it undoes your crouch. There is a recharge time to the crouch, but it's not very noticeable after the first time.

Smoker: Your reticle will light up red when you're in range and able to hit a target. Don't bother smoking otherwise, it just gives your position away and forces you to recharge.

Boomer: Remember that your dead body can blow up on survivors too. The Boomer's attack takes a VERY long time to recharge, and the Boomer is easy to kill otherwise. Most of the time if you've not been killed after your barf, you should try and get into the middle of the survivors and have them kill you at close range. You can use your LT to attack them while you're running around.

Tank: This is perhaps the second hardest infected to learn. The first thing to learn about the Tank is that his primary attack is RT and that there is a delay. After you hit RT, there's a slight pause before the Tank actually swings. Anticipate for that. LT is used to throw stuff, but nobody in the clan has really figured out how to do that effectively yet.