-Starcraft II
Make Marines.
Make Marauders.
Make Medivacs.
Make them attack the enemy.
Enjoy a refreshing victory drink.
Seriously, in 1v1 matches, this works so effing well it's not even funny. Anything more than one enemy, and don't bother, by the time you're finished with one guy, the other will have so much air support it will turn your marines into scrap metal and hamburger, and your Medivacs and Marauders will just sit there all useless-like as they are blown to shit by the air troops.
-Doom and Doom 2 and all their expansion packs and level packs.
Always use the goddamned shotgun. If you walk into a room that has a bit more heat than you'd like, feel free to take out the chaingun and calm things down a bit, but other than that, just point at what you don't like with the shotty and Swiss-cheese-ify it. And I mean the pump-action regular shotgun, not that breakdown piece of shit that just pisses away two shells.
-Team Fortress 2.
Spawn as Pyro.
Press W and M1. Aim yourself at things you want dead.
Press M2 if there is an incoming projectile from a non-hitscan weapon.
Enjoy another refreshing victory drink.
-Fallout 3 and FNV (and Morrowind).
Junk is not junk if you get cash for it. At the beginning of the game, pick up everything. Tin cans, soda bottles, scrap metal, it doesn't matter. Everything has value. Don't try this in Oblivion, though, because shit can have a "0" for a value there.
-Oblivion.
Just because not all trash is treasure doesn't mean you're screwed as far as money goes. Get a mortar and pestle, get food, and make potions. Sell them to alchemists. Go visit farms and steal all the food. Then make more potions. You will be set for life for money. And to think, most NPCs in that game make less than five gold in a year! Those morons. Yuk yuk.
And that's all I can think of off the top of my head.