Everyone makes mistakes. The thing is, a good player will learn from them while a bad player will make the same mistake over and over again. And poker players that can exploit these mistakes will win.Here are some of the most common mistakes that bad players make and my usual methods for exploiting them: A player doesn't bluff enough. When these players bet or raise, I usually give them credit for a good hand. Whenthey check, I will usually bet to try and take the pot. A player overvalues top pair. The "average" winning hand in Hold 'em is two pair. Yet many players are willing to take tremendous risks with top pair. When I have a hand that can beat a player who overvalues his top pair, I will over-bet the pot and put them into a position to make a big mistake. I go out of my way to play small pocket pairs against these players because I know that if I flop a set, I'm likely to get paid off in a huge way. A player under-bets the pot. It is incredibly important, especially in No Limit Hold 'em, to make bets large enough to punish opponents for their draws. When a player under-bets the pot and I have a draw, I take advantage of their mistake by just calling the small bet. When I think I have him beat, I'll make a raise. A player calls too much. I will very rarely bluff against a "calling station." I will,however, make value bets throughout the hand. A player tightens up under pressure. Most bad players "squeeze" too much in the middle stages of a tournament, or when they're on the bubble. They tighten up and wait for a huge hand. Against these players, I will play a lot looser, looking to steal a larger share of the blinds and antes. A player telegraphs the strength of his hand with "tells." I am always observing these players, whether I am in the hand or not. Playing perfect poker may be nearly impossible for most players but, by recognizing your own tendencies - and those of your opponents - you're much more likely to limit your mistakes and capitalize on the weaknesses of others at the table. This lesson is from Phil Gordon's Little Green Book of No Limit Hold'em Simon Spotlight Entertainment, Sept 2005.