Don't Expose Yourself

A good rule of thumb when playing poker is not to reveal your cards unless absolutely necessary. While you are obviously not going to go around showing your hand while you are playing a round, you shouldn't let the rest of the table see your goods when you're out either. When you fold place your cards face down.

Why? First of all, many professionals have a knack for being able to better speculate what other players have in their hands by seeing what you had. No one is helping you win so why should you assist someone else?

Additionally, if you win a hand by bluffing, don't reveal your cards. Instead, lay them face down and allow the cards to be shuffled for the next round. This way, other players will not be able to see what you had up your sleeve. If they become aware that you were bluffing they may become hip to your game and take note of your mannerisms. A good poker player never reveals his tricks.