For better or worse, Peter Lynch is the "buy what you know" guru.

Even though he's said he didn't mean that exactly, "buy what you know" is an incomplete guide to beating the market. It suggests that some of your best investing ideas will come by snapping up shares of companies behind your favorite products or by trolling the mall. And when I first read it as a twentysomething investor, I embraced the simple notion of acquiring the familiar.

But it's not so simple.

The other half of "buy what you know"
The problem is that "buying what you know" is just the first step to beating the market. Once you take it up a notch -- going from One Up on Wall Street to what I will call Two Up on Wall Street -- you will realize that the second logical step is even more important.

That second step? The missing ingredient from Lynch's once tantalizing investing recipe?

Buy what they don't know.  

Calling off the Lynch mob
After all, I can live my life singing the praises of Apple (Nasdaq: AAPL). I finally ponied up for a MacBook last month. My son is perpetually tethered to his iPod. When it's time to upgrade my cell phone this year, my one and only consideration is an iPhone. That doesn't mean that I will make a mint on the company. In fact, I probably won't at this point, because everybody already knows the Apple story. The real money in Apple was made several years ago when the iPods were just starting to gain traction, or even more recently when the "I'm a Mac, I'm a PC" ads started to catch on.

So it's not necessarily about buying what you know. It's ultimately about buying what they don't know.

Some of my favorite investments -- and, I bet, many of yours -- have been companies that grew in popularity after they camped out in your portfolio. I bought Jones Soda (Nasdaq: JSDA) just as the soft drink company stumbled in its initial rollout of canned soda. I got in at a fair price and I'm confident that the stock will bounce back.

The pop world can use an edgy disruptor. The established titans have the personality of a thimble. In the meantime, I'll keep downing the mainstream and seasonally offbeat flavors in the Jones Soda family. I'm buying what the rest of the market doesn't know, and it's sweetened by cane sugar.

Zig before they even think of zagging
As a member of the Rule Breakers newsletter team, I try to spot emerging trends early to try to profit from being early to the party. David Gardner's newsletter is all about buying what they do not know.

Steiner Leisure (Nasdaq: STNR) shares are up some 80% since I recommended the stock to newsletter subscribers a couple of years ago. The provider of spa services on most of the major cruise lines has had a great run -- to the chagrin of skeptics who felt that the company would be toast if the cruise ship heavies like Carnival (NYSE: CCL) and Royal Caribbean (NYSE: RCL) went for an in-house solution. Some have tried, failed, and come back to add even more ships to Steiner's growing fleet.  

Blue Nile (Nasdaq: NILE) is another of the market-thumping picks for Rule Breakers. The online jeweler is the undisputed champ when it comes to selling high-end diamond engagement rings online. I've heard cynics argue that traditional jewelers will make a bigger splash in cyberspace. Isn't it a matter of time before low-end players like (Nasdaq: BIDZ) go upmarket?

Well, it hasn't happened yet. More important, Blue Nile has gone on to blow away Wall Street's expectations in every quarter but one since going public nearly four years ago. I knew about Blue Nile when David Gardner recommended it. The real kicker is that most investors didn't -- and still don't -- know it.  

Buy what you know better
When you invest, go to the mall; ponder the contents of your cupboard; question why you chose one burger joint over the other. And when you unlock that desire to be inquisitive about equities, also figure out what you know -- and what you see -- before the rest of the market.

That's what we do at Rule Breakers -- and you can sign up to see our picks today by clicking here with no obligation to subscribe.

This article was originally published on Nov. 2, 2007. It has been updated.

Longtime Fool contributor Rick Munarriz wonders whether Peter Lynch will ever read this article. He still owns shares in Jones Soda, a Rule Breakers recommendation. Royal Caribbean is a Stock Advisor recommendation. The Fool has a disclosure policy.