Rules for Online Multiplayer Games in General (transferable, I hope):
1- Learn to Play to Win (by extension, "There is no Cheap"). Look up David Sirlin's site or book if you can, this tip alone is worth it.
2- Learn Map Awareness. 9/10ths of ganks on a newb happen when is "head is down", and are preventible.
3- Learn to do the Dirty Support Jobs nobody else will do (ie playing medic, chasing down enemies in your back field, fixing tanks all game). Heal botting, engineering, or fixing tanks don't make for sexy Linkin Park montage music videos, but they win games.
4- Learn to hunt down the "noob tube" or "low skill entry" weapon in any game, and whore it until you get better. Haters are going to hate, but at least you will help your team win.
5- Play The f!@#$ing Objective.
6- Stop K/D whoring and Play the f!@#ing Objective!
7- If some tactic, weapon, or unit is really cheap/powerful and is being used against you, get it yourself and start abusing it yourself. One of two things can happen here:
A- you either get the counter shoved in your face and you learn yourself what the limitations/challanges behind your cheap ability is, or B- You become an un-killable God. You Beat the Game, Congratulations.
8- Watch youtube "let's play" videos of experts playing the game. Look for full game clips, not "montages" and watch how the pros do it. Try to emulate their play style, and what they are thinking when they play. When they screw up, find out why they screwed up. Learn from their triumphs and mistakes. Any decently competitive online game (see: LOL, Starcraft 2, Battlefield: BC3/BF3, Call of Duty series, HoN, etc) will have loads of these online, and they are usually free.
9- Take a look at the button configuration in a game's keybinds to see what abilities are available to you as you play. (I learned that the V key in Battlefield 3 switches your firing modes between single/burst/full auto for instance). As an extension to 9, find a good keybind set that works for you and try to stick to it game by game.
10- Learn from your mistakes, and don't be afraid to lose. Mistakes and bad games don't become failures unless you fail to learn from them on what went wrong. You also learn far more as a player from a tough fought loss than a ROFLstomp win. For every killwhore montage video you see on youtube, that player probably had 5 shitty games where they got rolled, or was learning the ropes off camera, so don't be discouraged.