Before you make a decision whether to fold, call or raise (and how much to raise if NL), think about the reason you're about to do it. If you can justify it, then great. You can look back on your play and determine if your reasoning was correct or not. If you're just out there playing by feel or calling just because you want to see the next card/what they have, then you're not thinking through your play and you'll never improve it. In order to improve what you do, you have to know why you do it.

Before you make that call of your opponent's all-in bet, think about the chances of them having a better hand than you. How many ways can they have a hand that beats you? What was the action up until now? Try to put your opponent on a hand before you call or fold. Even if you hold a straight flush and they put you all-in, try to put them on a hand. It will be good hand-reading practice.

Accept responsibility for your play

Yeah, yeah, you took a bad beat. If that card hadn't come on the river, you would've scooped a nice pot. Good job. You played correctly until the river card came and then you lost your stack. Play correctly on every street and don't blame the outcome on the cards. If you're blaming your luck or the cards/dealer, then you're not reviewing your play. I think a lot of people steam over their luck and never spend that time reviewing their play. Thinking about what could have been isn't constructive and is just a waste of your time. More importantly steaming over your luck could get you on tilt.

Conversely, if you suckout on someone, rejoice for a second or two and then review your play of the hand and determine how you could've played it better. Did you have pot odds? Did you get paid off once you hit? What would you do in the same situation if you had to do it over again.

Don't think that your opponent plays like you

I make this mistake way too often. I often think that my opponent thinks like me and play accordingly. He wouldn't bet on the river without a great hand on this board. He wouldn't call a bet unless he had me beat. People are not you. Therefore, they play much differently than you. Don't make your reads based on what you'd do if you were in their spot. Make your reads on what you think they'd do in their spot. This one has cost me a lot of money.

Check out doubleas's book, Pressure Poker: Poker Strategy and Tools to Improve Your Game (also available in the PokerSavvy Shop)