If there are three or less in the pot, I lead the flop because I may take it there. With four or more in the pot I check and lead on the turn. I like to take control of the hand as soon as possible and begin chasing out players looking to boat their set... just like outbetting a flush or straight draw. worst case scenerio is that your opponent has put you on chasing a flush with their set and they check the turn looking for another pair. I try not to slowplay at all, of course some situations call for it however. Usually though, I'm leading the betting when I'm ahead.

Someone once said: "The trick to Hold'em is getting the most money in as possible when you are ahead." Actually, I think this is common practice.