1) The front line - Where the action happens. This'll shift as the game progresses, but it's the only place to score points.
2) Robot wars - Best left hanging back so they don't get shot while they're fiddling with their controls. Make good use of them.
3) Sharp shooters - Spawning this far back isn't always advisable, but it lets you get your bearings and gear yourself up.
4) Let's roll - Tanks spawn at preset points and can be tagged by either team. Getting a convoy together is a great feeling.
5) Bomb the base - These can hang back and still cause massive devastation.
6) Brand new heavies - These boys are vulnerable in close combat, but essential for taking down tanks. Protect them.
7) Hello Nasty - Shotguns are brilliant for infighting, but they're helpless against tanks.