Forbes just released its 2007 list of the richest Americans. The 2007 edition was particularly notable because you had to be worth at least $1.3 billion to be included.

As you might expect, a significant number of the folks on the list made their fortunes by investing. That subset includes Warren Buffett (worth $62 billion), Carl Icahn (worth $14.0 billion), and Jim Simons (worth $5.5 billion).

So here's important lesson No. 1: You can make a lot of money if you learn to manage your portfolio like a pro.

Easier said than done ...
Of course, that collection of billionaire investors offers no clue regarding what strategy is most likely to make you a billionaire. Buffett is a dyed-in-the-wool value investor. That strategy has helped him grow book value at more than 20% annually at Berkshire Hathaway for more than 40 years, on the back of investments in boring companies with competitive advantages at good prices such as GEICO, Moody's (NYSE: MCO), Coca-Cola (NYSE: KO), and American Express (NYSE: AXP).

Simons, though, can point to 34% annualized returns at his Renaissance Technologies' Medallion fund since 1982, net of what are believed to be some incredibly stiff fees. He favors a mechanical strategy, based on computer models that are constantly refined by an army of Ph.D.s.

So while there is no best strategy, important lesson No. 2 is obvious: You gotta dance with the one that brung ya.

Say what?
Colloquialisms aside, all of these investors are astoundingly successful because they've figured out how they make money best, stuck with their strategy in good times and bad, and refined their best practices over time.

Buffett was mocked during the technology bubble when companies that he avoided -- and professed to understand more poorly than others -- were zooming to the moon. But they've come back to earth, and Buffett's doing just fine today.

Icahn has a reputation as a corporate raider; he's made a lot of money instituting changes at underperforming companies. And while Icahn's efforts at ImClone (Nasdaq: IMCL) got off to a slow start, the stock has done well since September following the release of some positive Erbitux data, and he may also be able to exact some changes at Motorola (NYSE: MOT) yet. Why mess with success?

And Simons doesn't try to analyze businesses as Buffett does, because that's not where his expertise lies.

Mimic the masters
The secret to successful investing, then, is not found in any single strategy, but rather in picking the strategy that's right for you and executing it faithfully. As lauded NYU finance professor Aswath Damodaran writes in his book Investment Fables, "Each strategy has the potential for success if it matches your risk preferences and time horizon and if you are careful about how you use it."

That's it. That's the secret. Because if you get too cute -- chasing hot sectors, buying high and selling low, and giving yourself only six months or less to master a given investment strategy -- you're simply setting yourself up for failure.

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This article was originally published on Sept. 30, 2006, as "Join the Billionaire Boys Club." It has been updated.

Tim Hanson owns shares of Berkshire Hathaway. The Motley Fool also owns shares of Berkshire Hathaway. Berkshire Hathaway, Moody's, and Coca-Cola are Inside Value choices. Berkshire Hathaway and Moody's are Stock Advisor choices. The Fool's disclosure policy assures you that no stocks were harmed in the writing of this article.