As a Heavy, remember to give a burning medic your sandvich instead of stuffing it in your face while he burns to death.
As a Pyro, remember to find the right click on your mouse, it's pretty useful.
As an Engineer, you can right click to rotate teleporters, so your teammates aren't facing walls when they use it.
As a Soldier, don't rush up to a medic screaming for help while you have the Equilizer out, they can't heal you because of it.
As a Scout who uses all unlocks, remember not to: Fail at stunning them with the Sandman, then snipe them with the Fan, only to pitifully attempt to run away with Bonk! only to be caught in the slow down effect.
As a complete douchebag, remember to do one of the following:
Spam loud excessive noises into the microphone.
Tell people there's a spy behind them when there's not.
Become the class your team has the most of, bonus points if it's a Scout.
Block friendly Snipers, only to watch them get headshot instead of you.
Rant on about how your team sucks when you're clearly the on the bottom of the scoreboard
Awesome tips huh guize?