I usually just follow CADs' commandments of gaming, and it gets me by.
Thou shalt not kill steal
Thou shalt not frag... without gloating in the aftermath
Thou shalt lose graciously; thou shalt not bitch nor whine when fragged
Thou shalt accept thy dice rolls as the will of the Gods
Thou shalt teabag only in the wake of unquestionable ownage
Thou Shalt not cheat nor support the farming of gold
Thou Shalt not covet they neighbors' rocket launcher; Thou shalt not covet thy neighbors' epic mount, nor his video card, nor his high score.
Know thy group function; Thy DPS shalt avoid aggro, thy tank shalt not attempt to DPS, thy made shalt not forget mana potions, and thy healer shalt not go afk without notifying thy group.