a Really good book that you should read is Harrington on Hold'em Volume 1.
I can recap a little of what he says, but it is completely based on your style of play, and the play of the SNG you're in. If you're playing against a bunch of loose/aggressive players, you're obviously going to want to play tight and very selective. Against those loose/aggressives you'll throw away nearly everything in early position aside from AK, AKs, AA-JJ. In MP you'll play the big suited broadways as well, and occassionally limp in with the smaller pairs if the pot hasn't been raised. Your options grow slightly in LP, but not much. Big suited connectors like 9-10 and 10-J can be limped in with.
If you're playing against a feild of tight/weak players, then you should certainly open up your starting hands greatly. If no one is callign with anything but AA, KK QQ or AK, then playing hands like KTs or QJo from early position on a raise isn't a bad idea. Basically, against a group of tightwads, you have to play super aggressive.