Gary Bielfeldt is a trader profiled in Market Wizards
I learned how to play poker at a very young age. My father taught me the concept of playing the percentage hands. You don't just play every hand and stay through every card, because if you do, you will have a much higher probability of losing. You should play the good hands, and drop out of the poor hands, forfeiting the ante. When more of the cards are on the table and you have a very strong hand -- in other words, when you feel the percentages are skewed in your favor -- you raise and play that hand to the hilt.
If you apply the same principles of poker strategy to trading, it increases your odds of winning significantly. I have always tried to keep the concept of patience in mind by waiting for the right trade, just like you wait for the percentage hand in poker. If a trade doesn't look right, you get out and take a small loss; it's precisely equivalent to forfeiting the ante by dropping out of a poor hand in poker. On the other hand, when the percentages seem to be strongly in your favor, you should be aggressive and really try to leverage the trade similar to the way you raise on the good hands in poker.
Source: Market Wizards