This article's swaggering headline smacks of exaggeration -- but it's true.

How it happened
Picture it: New Jersey, 1995. Although not then a Motley Fool employee, I was, perhaps like you, an avid reader of Fool.com. Founding Fools David and Tom Gardner occasionally recommended stocks, and one of their recommendations was an online service provider, America Online.

I was still quite new to investing, and I didn't know enough to do much of my own research. But I did have one thing going for me: I was an AOL customer. I used the service every day, and I liked what I saw of its user-friendliness, utility, and potential. So I bought. I snapped up $3,000 worth of shares and hung on.

Over the next several years, the stock went up and down, sometimes significantly -- but I held on. It mostly went up, and it split and split. I remember checking my portfolio regularly -- several times a day! -- to see how rich I was becoming. Near the stock's peak, I had a 70-bagger! My $3,000 investment had turned into $210,000. If it doubled in value only twice more, I'd be (almost) a millionaire! All from a measly $3,000 investment.

Did I sell shares along the ride up? No. (Some of us don't know when to cut our losses.) Did I sell at least somenear the top, when my mom told me to? Nope. (That strange thudding sound you hear is me banging my head on my desk. The silence is my mom, biting her tongue.) I held on.

AOL merged with Time Warner in 2001, and for years after that, the stock struggled. I remember when shares were priced in the $70s (that would be north of $200 now, after a recent 1-for-3 reverse stock split), but it's a fuzzy memory. They spent years below $20 ($60, split-adjusted) until relatively recently, and even more recently drifted much lower. I did sell a big chunk of my shares a few years ago, when I needed money for a down payment on my house. And I finally got smart -- I sold more shares to diversify into other stocks instead of holding a big chunk of my net worth in a company in which I no longer had faith.

I continue to hold a few shares, though, and despite my inclination to curse my stupidity for not selling earlier, I'm still sitting on a handsome profit, even at current levels. My cost basis is ridiculously low, and this has stillbeen one of my best investments ever. I shouldn't complain.

How you can do it
If any part of this story appeals to you, know that you have a chance to make it yours -- perhaps with a happier ending -- if you make a few decisions differently. (You might end up as an accidental billionaire!)

Buy what you know
First, pay attention to products and services you know, use, and love -- especially if you see more and more people using them. There may be a great stock behind them, and knowing their products or services will go a long way toward understanding the business. Plenty of well-known companies have done phenomenally well over the past decade or two -- let's look at a few.

Have you been getting a lot of prescriptions filled lately? Well, CVS Caremark (NYSE: CVS) shares have increased in value about seven-fold over the past 20 years. Cell phone companies have done well, too -- with Nokia (NYSE: NOK) shares averaging 14% annual growth since it went public 14 years ago. Are those some Nike (NYSE: NKE) sneakers on your feet? Despite the market swoon, Nike shares have averaged more than 11% growth per year over the past decade, trouncing the market's return. Love your desktop computer or your trusty printer? Hewlett-Packard (NYSE: HPQ) shares have averaged 14% growth over the past 20 years. These companies have performed rather well, right under our noses.

Beware what you don't
Along those same lines, be wary of what you don't understand. If you don't understand how a business makes money, you probably won't be able to tell when business is going badly. Biotechnology companies present a good example, as do new-technology companies. Think of Amgen (Nasdaq: AMGN) -- if you're invested in it, do you have a good grasp of its multiple treatment modalities -- large-molecule proteins, small molecules and antibodies -- among other things? If you're invested in Oracle (Nasdaq: ORCL), do you have a solid handle on the database software industry?

Hang on for the ride
If you buy into a company hoping that it will be a multibagger for you, buy to hold as long as you continue to understand the business, strategy, and leadership. If you have faith in the company's future, it's often best to just hang on, despite inevitable hiccups. If you still have long-term confidence, don't let naysayers in the media get you out of a stock because of short-term concerns.

Consider the home-building specialist, Toll Brothers (NYSE: TOL). For some of its earliest investors, it's a 19-bagger over the past 20 years. For those who've hung on for just the past decade, through some down years and the market's recent upheaval, it has still averaged a 16% annual gain, far surpassing the S&P 500. So -- not bad, eh?

Sell if things get too crazy
Consider selling some of your shares if they hit levels you can't justify or if the company is facing some long-term problems. That was my main mistake -- irrationally and greedily hoping to get even richer. If a stock is trading for far more than you know it's worth, and you still hang on, you're no longer investing -- you're speculating, and at great risk. Continued...