If you're playing high enough stakes that preflop raises tend to take down the blinds and people know about position, your preflop raises should be entirely based on position. You should raise about 2.5x BB in EP, 3 BB in MP and 4 BB in LP (this according to chris fergusson).

However, I'm guessing you're not playing in that kind of a game. In that case, standard raise is about 4 or 5 BBs if you're first in. Otherwise, about pot size is what you wanna go for.