From the December 2006 issue of Entrepreneur

In a world where money means everything, deal making makes all the difference. To paraphrase negotiating expert Chester Karass: In life, you don't get what you deserve, you get what you negotiate. That's why bad deals sting so sharply. There you are, just like Jack with a handful of magic beans. Shame on you.
First, don't be so hard on yourself. Bad deals happen, even to the best of us. Your lawyer spaces out, the other side undercompensates, or the gods conspire against you. Accept what you can't control. Make lemonade and so on.

Are you a perfectionist? Does your mojo wither at the prospect of leaving money on the table? Lighten up. The answer to the question of whether you could have done better is always yes.
And if you screwed up, be big enough to admit it. Ask tough questions: Did you contribute to the problem? Did you communicate clearly? Did you forget something? How will you make sure it doesn't happen again?
Be introspective. Why did you goof? Should you have gotten help? Did you drop your guard? Were you too greedy? Too personal? Enlist a buddy and talk it through.
Above all, forgive yourself. The more mistakes you make, the more you can learn. And as Oscar Wilde said, "Experience is the name everyone gives to their mistakes."

A speaker and attorney in Los Angeles, Marc Diener is author of Deal Power.