Medium or hard depending on the game

easy on shooters/racings

normal on fighting games

hard on rpg/action/puzzle types

easy or normal. to be able to enjoy the story.... then I'll play the harder difficulties to get trophies

I find that the easy setting is too easy so I usually stick with normal. If I'm fairly good at the game, then I'll up the difficulty.

I usually start out on medium if I hear it is a very hard game or that the hardest mode should only be attempted by leveled characters. However, if I haven't heard anything specific about its difficulty, particularly if you can start with a level 1 character with no abilities or weapons on the hardest setting and survive, then I start on hardest difficulty. Most recent game that comes to mind is Torchlight. I started it on hardest difficulty and had little trouble. However, I doubt I'd have ever gotten anywhere in Oblivion if I'd maxed the difficulty lol. ~100 shots from a bow kills the lowest of level creatures on max difficulty.