What's your worst investing mistake? Mine was buying shares of Cisco (NASDAQ:CSCO) during the deflation of the dot-com bubble in 2001. I had listened to a tip from my then-boss -- no research, just her say-so. That was a big failure for me.

But I learned a lesson from that experience: Don't buy a stock just because someone gives you a name. After all, it's your money on the line, and it deserves to be put in the best places possible.

So where are these best places?
According to Wharton professor Jeremy Siegel, the best place for money not needed for several years is the stock market. Yeah, I know. The S&P 500 index has gone exactly nowhere for the last 10 years. In fact, it's down 17%.

So what? Unless you're putting all of your money into that index and ignoring individual stocks, that stat shouldn't concern you very much. Plenty of companies have outperformed the index over the past 10 years. Nearly 20% of the companies in the S&P 500 -- 93 to be precise -- have at least tripled over the past 10 years. Companies like PACCAR (NASDAQ:PCAR), up 333%, or Apple (NASDAQ:AAPL), up a cool 1,000%.

Further research, of course, would have been appropriate before investing in one or the other. "Were sales growing?" and "What did free cash flow look like?" were just two of the many questions investors needed to consider before deciding.

Here's your hot tip
Of course, we want the companies that can do the same over the next 10 years. A great way to find ideas is to look for companies with earnings the market underappreciates, which simultaneously have a healthy return on equity (ROE). These metrics can help you to identify companies that are not only cheap, but also have good operations. In the fall of 1999, PACCAR had a price-to-earnings ratio (P/E) of 8, and an ROE greater than 25%. While Apple's P/E was moderate, it was low compared to its history, and its ROE also topped 25%.

Here are a few companies that fit those criteria today:

Company

Market Cap (billions)

Trailing P/E

Trailing ROE

Chevron (NYSE:CVX)

$153.7

9.4

19%

Noble (NYSE:NE)

$10.7

6.6

29%

Patriot Coal

$1.0

4.9

20%

Transocean (NYSE:RIG)

$27.1

7.4

22%

UnitedHealth Group (NYSE:UNH)

$30.7

8.9

17%

Sources: Capital IQ, a division of Standard & Poor's, and Yahoo! Finance.

Of course, that's just a list of companies that meet a certain set of requirements. You should still perform further research to see whether they're worth your dollars. For example, consider whether oil drilling will increase before you invest in ocean-driller Transocean. And ask, "How will Obamacare affect insurance companies?" before putting money into UnitedHealth Group.

But once you've answered such questions, investments in companies similar to those will likely do better over time than any attempt to follow the crazy antics of either poisonous or dangerously overvalued companies.

Further aid
If you'd like some assistance, we have a resource that can help you vet companies like those listed above: Million Dollar Portfolio. This real-money portfolio invests $1 million of the Fool's own money in the best of the more than 300 companies populating our newsletter-recommendations universe. So the companies have been researched once -- before their appearance in one of our newsletters -- and then again, before they're actually purchased in MDP.

Lead advisor Ron Gross uses his nearly two decades of experience in stock analysis and money management to lead his team in picking the best companies to invest in. One of the names above, dual newsletter choice UnitedHealth Group, is a current MDP holding.

For 10 days beginning Nov. 10, we're opening membership for the first and only time this year. For your invitation to see our research in action, picking and choosing among our newsletters' best recommendations, enter your email in the box below.