Some information on how to play the Special Infected. This is specially compiled for those noobs!

Boomer
The big daddy of all that is vomit inducing, The Boomer’s speciality is disruption. Its bile attack is designed to help the other SI split up the Survivor team by obscuring their vision and calling in a horde of flesh hungry city folk to rip them to shreds. It is one of the most important SI in any ambush attempt and although 1 shot will kill you, you can do plenty of damage even in death. When the Boomer is killed it lets out a small explosion that knocks the survivors backwards 2-3 ft, you can time this right in many locations to knock the survivors off a ledge or through a window. Most important factor of Boomer play is your spawning, he makes a lot of noise and can easily be pin pointed through a wall. Spawn as late as possible and as close to the survivors as possible. If there is a Spitter ready to spawn communicate with them and tell them what you’re doing, human instincts mean that people will find a corner once a Boomer hits them, combined with the Spitter it results in one of the most deadly double attacks in the game.

Spitter
Probably the most loved of the second generation of Special Infected, The Spitter was designed to combat “Shiva Stacking” and “Corner Camping” that were so evident in the original L4D. The Spitter is able to surround survivors with acid causing damage over time that gets more severe the longer they are exposed to it. The Spitter is one of the few SI that can do damage without ever being seen, the spit mechanic is brilliant and it allows you to bounce the spit down walls or across gaps meaning you can attack from out of sight. A Spitter is next to useless alone unless you’re spitting on a incapacitated survivor so make sure to wait for one of the other SI to assist you. Spitters main objectives are to keep pinned down survivors moving and aid in keeping an incapacitated survivor down. Never spit at moving teams.

Hunter
My personal favorite and one of the most skill intensive Special Infected. The Hunters main task is pure damage, it is the single most damaging ability in the game and can destroy a lone survivor in mere seconds. The Hunters main attack “Pounce” is able to bounce off walls, scale the tallest buildings or slide down a railing. By using air strafe techniques you can take total control of your Hunter and pounce from rooftops to hit massive damage. The longer the distance of the Pounce, the more initial damage you do on impact. Single, high damage pounces are the way to play a Hunter but don’t camp a location for ages, if you’re inside a building or enclosed space, assist your team mates. There is nothing worse than having to attack with 3 SI for 5 minutes because your Hunter is poised on a building half way through the level.

Jockey
A small deformed dwarf? I’m not really sure what the Jockey is supposed to be but it is damn ugly, and it rides your face! Jumping on to any survivor will allow you to control the direction they move in, this can cause a large amount of problems for any survivor team. Your main duty as a Jockey is separation, riding a survivor to a location out of sight so that your team can pick apart the rest. Your primary goal of any attack is to make the Survivors go backwards, never grab a survivor and take them the way they’re meant to go as it very rarely ends well. The best location to demonstrate the Jockeys ability is No Mercy 3, the gas station. Ride a survivor right up to the pumps and watch his team mates blow the station and send their poor team mate to oblivion in pieces. One of the most effective SI in the game but it takes practice.

Charger
Awesome, just pure awesome. The Charger is the bowling ball of Special Infected. His main attack launches himself towards a survivor, picking them up and running as far as it can before repeatedly smashing the survivor into the floor or ceiling. Some have-a-go-hero always attempts to get in your way and shoot you but the pure power of the Charger sends any survivor he runs into flying in random directions. The best use for a charger is distraction, especially in small areas. Corridors/windows etc The Charger is built for these as you can run people right off a building or get a strike and smash all 4 survivors to bits down a hall way. Remember to attack from behind as your initial roar when activating your attack will give your position away ending in a swift death if you’re in the Survivors field of vision.

Smoker
One of the most tactical Special Infected in the game, The Smoker launches a 200ft tongue out at a survivor in the attempt of wrapping them up tortilla style and dragging them back to scratch out their face, it really is quite a brutal zombie. The Smoker is all about control, you have full control of where the survivors must go to save their team mate, this is usually best demonstrated by forcing Survivors to back track and reclaim a team mate. There are many areas in the game where a Smoker can instantly kill a player by dragging them out a window or off a cliff, experience will show you the better spots.

Tank
One of the most misused classes in the game yet one of the most vital. A Tank on any level is a pain to play, the Survivors are well rehearsed in setting you alight and running for the horizon. You’re useless alone in a wide open area so don’t even try, hide away and wait for a Boomer or another SI to attract enough attention to give you time to attack. Only use your rock throw if you’re out of the line of sight of the Survivors.