Rule #2

Teamwork is always key. 

Regardless if you are playing a single player game or a multi-player game.

Making sure your team survives is just as crucial as your own survival.
In L4D(2) you shouldn't ever stray far from your team. In FPSs you should cover your teammates (rambo-ing isn't always effective). In LoL don't fight their team solo.

Use teamwork and don't insult your allies (if multiplayer) and your chances of success will skyrocket!