pre-flop raises amounts in nlhe

i've only been playing nlhe for about a year now, but i found a pretty good small stakes game. ($20 buy-in 25 and 50 cents blinds) my question is should i vary my pre-flop raises or always raise the same amount regardless of whether or not it's aces, big-slick or just a pair of 8's. i guess i'm just trying to guage what other people do in their small-stakes games. i'm still pretty new so try to not be too harsh. i also take position, and the amount of players in the hand when determining whether or not to make a raise in the first place. if anybody's got some advice that would be awesome.

kevin