Don't dick around
Obviously. It's a heavily team-oriented game. When you dick around it's fun for you but hell for the rest of the team.
Do not Feed
Same as above, you screw over your team. Equivalent of mining all your team's vehicles in FH2. Bannable offense.
do not farm
BS, that's half the game. If you're carry, this what you're made for. If you're support, you help your carry farm.
do not play squishy characters
...if you can't play them. You'll just end up feeding, effectively throwing the game.
noob Anti stop feed юбоний сука идиот!
(Also so many russians)
TL;DR: Learn to play.