Mistakes

One principle of poker is that you make money whenever your opponent makes a mistake. [@@]

One odd case is that sometimes you can make money no matter what your opponent does.  Let's say the pot has size P and you bet 1 chip at it.  Your opponent is on a flush draw, ...... [@@]

A very common mistake that people make is to overvalue pocket pairs.  In No Limit, these means that if you have AA, you can usualy get someone with something as poor as JJ to call you all-in.  Also, many people play pocket pairs and flop something under the board, for example if they hold 99 and the board comes 6TK.  That 99 is now actually a very poor hand, for example T2 or T3 are better, but many people still think of the 99 as somehow "a good hand".  You should not only avoid making this kind of mistake, you should watch for it in others and profit from it when they make it.

Probably the most common mistake in low limit Hold'Em is that people call too much.  You take advantage of this simply by betting when you think you have the best hand.  It will mean that they sometimes hit their miracle cards, but they pay you in the long run.

Many good players get frustrated when their opponents make mistakes.  Don't - in fact, try to tell them "good play" and encourage them to keep making that mistake.  Remember it and take advantage of it.  If someone makes a horrible call with bad odds and they "river" you, tell them "nice hand", and then take that money  back from them by playing better than them.