In his book "making the final table" Eric Lindgren does an excellent job of explaining when it makes sense to keep the pot small and when you need to start throwing hay-makers. Basically, in situations where you are either way ahead or way behind (ie. few draws available on the board)it makes sense to either bet small(half the pot or less) or just check and call. His reasoning is that you may lose a little more when you are behind, but you will make much more when you are ahead and your opponent tries to bluff you out of the pot. Also, he feels that you gain a lot more information from checking and calling in situations like this than leading out with a bet. This limits your exposure to the "bluff raise" when your opponent is just trying to use position to steal the pot and you are sitting there with something like top pair and a weak kicker......I suggest picking up a copy of that book. His post-flop strategy is excellent and has really helped my game.