Are you one of those people frustrated with your inability to beat the stock market? Despite watching CNBC and Jim Cramer religiously, and reading The Wall Street Journal every day, you just can't seem to make it happen. Here are five ways I think that investors shoot themselves in the foot.

1. Do little or no research before buying a stock.
Would you trust a stranger to take care of your kids or drive your car? Then why would you entrust your portfolio, your hard-earned money, to the hands of management teams and businesses that you hardly know?

If you want to make blind bets, head to Vegas. It's more fun losing money in a casino than in front of your computer. While you're at it, you could do a little research on casino stocks, and you'll see that the house always wins -- especially when companies like MGM Mirage (NYSE:MGM), Las Vegas Sands (NYSE:LVS), and Wynn Resorts (NASDAQ:WYNN) dodge their financial problems for an amazing 2009.

Remember, every time you buy a stock, there's someone on the other side of the trade. Consider these other people the "house." If they know more than you about the stock, you're at a disadvantage.

2. Buy stocks based on tips and rumors.
In my life, I've gotten two tips that could be construed as insider information, which I declined to act on. Both tips were of the "I have a friend, who knows a guy, whose cousin" variety. Anyways, I checked out the tickers about a year after hearing the tips, and both had plummeted.

3. Be an envious investor.
Charlie Munger often states that the worst of the seven deadly sins is envy, because other sins, like lust or gluttony, provide the sinner with pleasure. Envy, on the other hand, has no pleasurable aspect whatsoever.

I blame envy for a lot of things. I think envious investors bid stocks like eBay (NASDAQ:EBAY) and Yahoo (NASDAQ:YHOO) up to amazing heights during the tech boom, and Crocs (NASDAQ:CROX) to over $75 a share two years ago. I think envy drove Shaq and Kobe apart and effectively dismantled the Lakers dynasty -- at least temporarily. I also think envy causes the average investor to get swept up into bull markets and decimated in the subsequent crashes.

4. Invest with low conviction.
Doing a lot of research doesn't help much if you don't stick around to reap the benefits. I think investing without conviction is like marrying someone you just met a week ago. After the initial honeymoon phase, failure awaits after the first set of speed-bumps.

When investing in stocks, I can almost guarantee you won't catch the bottom. There are just too many random factors involved in the collective buying and selling activities of millions of people around the globe.

In fact, I think investing without conviction almost guarantees failure. Let's say you were smart enough to figure out that Apple (NASDAQ:AAPL) was a bargain back in 2001, and bought in the $10-12 range. The stock had cratered more than 70%, so investors could reasonably think that was the bottom of the barrel.

Unfortunately, everyone who invested in Apple's stock in 2001 would've seen their investment fall around 20%-30% over the next year. They'd also have to wait nearly two years just to get back to breakeven. Many investors would not have the conviction to ride out this storm, and would have bailed out at a loss. However, those with conviction who held on would be sitting on a 20-bagger, with the stock currently above $210 per share.

5. Fail to separate price from value.
Oddly enough, we have no problem distinguishing between price and value at the mall. We don't say, this Gucci handbag is worth $3,000. We say, wow, that handbag costs $3,000. What a rip. At the mall, we know that the price people want us to pay, and the value we receive, can be two very different things.

The same rules apply to the stock market. For most companies, share prices move around a lot more than intrinsic value. Sometimes the two move together, sometimes they don't -- but they're two very different things.

The investor who fails to discriminate between price and value fares no better than the tone-deaf contestant in American Idol. Both lack vital ingredients for success.

Final thoughts
So there are a couple of examples of what not to do. If you eliminate as many bad investing habits as possible, you might just turn into a great investor.

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This article, written by Emil Lee, was originally published on Sept. 10, 2007. It has been updated by Dan Caplinger, who doesn't own shares of the companies mentioned in this article. The Fool's disclosure policy never has a terrible, horrible, no good, very bad day.