Best premium hands are going to be pairs, like jacks and up, or like AK suited.
Depending on how the betting goes pre-flop, the flop can make a massive difference in what happens next - some people can limp in chasing straights and flushes and the flop is dramatic to them. People flop trips, or they flop an open-ended straight draw, or they have four to a flush, etc..
You don't have to show your hand when you fold, but sometimes it is a good thing to do so. If people think you are only going in on really good hands and nothing else, they can be conned into folding a good hand when you bluff later. I kinda play like this mostly, and people get fooled later. The problem arises when you are not dealt any good hands forever in the beginning you just fold and fold and it gets dull. But discipline wins in this game. If you can have your opponents truly guessing what the hell you can do on any given hand, you are in better shape than if they don't think that. You still have to play well though, you bluff too much one round when a guy has a monster hand and that could be the end of your night.