While playing poker for a few years now, I notice some common mistakes that every player makes. Most players are playing at a limit too high for their bankroll. If you play at a limit where you can not afford to lose, you will not play your best game. You will play with scared money and get pushed around by more aggressive players. Stick to a limit where you are comfortable bluffing, calling down with marginal hands, and making some advanced plays on your opponents. Even some of the top pros are playing in games that are way over their head. Bad bankroll management is the largest leak in any player's game. The top cash game pros use their big bankroll to push around opponents who are unwilling to put in money without they have the nuts. Slowly but surely, the under funded poker player will go broke.
A lot of great players would have even greater if they could control their tilt. Tilt occurs after a bad beat, a bad decision, or anything negative that may have occurred at the table. A player who is on tilt will often play well below his normal skill level. He will lose a lot of money in a short period of time because he is making terrible decisions. Learn to control your emotions and leave the poker game when you feel you are on tilt. Even the best players tilt from time to time, but they know how to leave the game. Many good poker players would be great poker players if they simply knew how to let go of their ego. Some minor success in tournaments can build ego and make a person believe they are the best player in the world. Ego gets in the way of the learning process and impdes a player from improving. To be the best, you have to remain humble. Every day, you should find ways to improve your poker game. By removing many of these leaks from your game, I believe success will come naturally.