2. Your first loss is your best.
3. It's OK to take a loss when you already have one.
4. Never turn a trading gain into an investment loss.
5. Tips are for waiters. Do your homework.
Commandment No. 6: You don't have a profit until you sell. Cramer said that a lot of people sit on their paper gains and then lose them because they don't want to pay the taxes they'll be hit with when they sell. But the amount you have to pay in taxes is nothing compared to the amount you could lose if you don't lock in the gain on your trade. Commandment No. 7: Control your losses because the winners take care of themselves. Cramer said that traders need to spend the bulk of their time keeping tabs on potential problem stocks because one bad apple can ruin a portfolio. "Don't say, 'I'll just wait for this one to come back and then not do it again. I'll wait for EMC ( EMC) to come back to $18 and then I'll be done with it,'" Cramer said. This is how people who lose money think, he said. Commandment No. 8: Don't be afraid that you're missing out. Cramer said that if this is your worry, then you're probably coming in too late. It's better to acknowledge that you've missed out on the opportunity and to move on to the next opportunity. Commandment No. 9: Don't trade on the headlines.