Cramer's 'Mad Money' Recap: Back to Basics

Don't Dwell on Regrets

The second worst mistake people make when they invest is harboring regrets, he continued. In his Real Money book, Cramer made this rule No. 13: "There are no woulda, shoulda, couldas." And even though people know it's unproductive and bad to dwell on missed opportunities or past mistakes, they still do it, he said.

"Every second that you spend wistfully wishing you'd made different decisions is a second wasted," Cramer said. "It's just human nature: We want lots of money, and when we miss an opportunity or make a mistake, we can spend hours or even days beating ourselves up over it."

In fact, Cramer said he's the worst trespasser when it comes to this rule. When he worked at a hedge fund and got something wrong, he'd "just sit there, totally mesmerized" and totally hating himself, he said. But market players "cannot afford to get thrown off their game" like that.

"So you need to be proactive," Cramer said. "When you make a mistake that you can't stop thinking about, you need to make sure you don't get mired down thinking about how you made such a bad decision."

Instead of thinking about the past, think about the future, as that's the only way to make money, he said. And second, don't let the mistake weaken your confidence.

Tips: For Waiters, Not Traders

The next rule is "tips are for waiters," Cramer said. He said he knows people like to get "hot stock tips" and "make easy money," but there's no such thing as a stock tip, and "you have to discipline yourself so that you never, ever take a tip seriously."

For example, if there is a person that gets a tip from a friend that Nokia wants to buy Research In Motion, "alarm bells should start ringing" in that person's head, Cramer said.

The only way the tipster could know that would be if he's an insider, and if an insider tips you off to the deal before it's announced, he's breaking the law, he said.

"Having the Securities and Exchange Commission investigate you is pure hell even if you haven't done anything wrong," Cramer said. "Imagine how bad it would be if you were actually guilty of something."

However, if the tipster is not an insider, then there's no way he could know that Nokia's going to try to take over RIM, he went on to say. And getting a tip from somebody who doesn't know anything is "worthless."

Although, people would love to get a real tip, "those don't exist," Cramer said. "If you get a tip, it's either illegal, incorrect or straight-up manipulative."