1. Don't play when you're in a bad mood.
You need to think about poker rationally, not emotionally. When you lose a big hand and are getting frustrated with the game, get up and take a break.
2. Try to be the last person to act.
When you have position on your opponents in a hand, you get additional information that can help you make the better decisions. You may have made a bet if you were first to act on the flop, but after seeing a bet and then a raise in front of you, you can safely fold and know that you are beat. Maybe you've flopped a straight draw and 3 people check ahead of you; you can decide to check and take a free card instead of risking a check-raise.
3. Don't call a river bet just to "keep someone honest."
Think through the entire hand. So many times I hear players say "I know you've got me" and then call. Trust your gut!
4. Don't keep playing because you want to get even.
Keep playing if the game is good and stop playing if the game is bad; it's as simple as that. Focus on the big picture and make good decisions. There will always be another game.
5. Don't give out free lessons at the table.
Don't tell your opponent how badly they played a particular hand or what you would have done differently. You don't want to discourage them from playing hands, especially if they are practically gifting you chips. And, if you're trying to make money at this game, you don't want to teach them anything that will make them a better player.
— Sarah Dygert' 10
Dygert also recommends two poker forums for those who want to advance their poker game: www.twoplustwo.com and www.pocketfives.com. The best way to improve your game, she says, is to post hands or talk to people in real life and get other people's opinions on what you did wrong or what you could have done better.