In this mod you must work as a team. If you run around like a deathmatcher then your team loses. You will have to set up a defense an offense and a scorer.
Typically the scorer will be a scout, because of the speed, and the defense will consist of demomen, pyromen, snipers, soldiers, engineers and medics. The offense should never have an engineer unless he intends to build a sentry gun inside the enemies base, but this will only get one or two kills. Offensively you will have powerful and speedy guys. The only exception is the HWguys because they have soooo much armor. As standard more demomen and soldiers, in addition to them try using a spy for brilliant infiltration [be warned though touching a scout or another spy will remove your disguise]. Then place yourself stratigically, don't hide in your supply room waiting for the enemy cos they can't get in there.
For more detailed tips on specific levels select a link below.
2Forts (Capture the Flag)
Well (Capture the Flag) [not working]
CZ (Capture Zones) [not working]