Let me tell you something about players that are constantly agressive. If you are playing against the type that always raises pre-flop, you should call with a marginal or good pocket hand to see the flop. Next, check the flop, since he will most likely bet into it if he has trash, and he may check if he has a good one.

So let's say you check the flop, and then he bets it fairly big. Assuming that no one else is still in the pot, you then raise his bet by slightly more than double his big bet. It doesn't really matter what cards you have, because he will most likely fold. This trick works for me about 90% of the time. Just don't use it very often. You have to pick and choose the right times, making it seem like you are very conservative. You should seldom call a bluff after just the flop, you should raise it.