If you want to be a wildly successful investor, you'll need to invest in some wildly successful companies (or mutual funds, or apartment buildings, etc.). But zeroing in on the most promising companies is easier said than done. One way I like to invest is to build a list of wonderful companies and then watch for their stocks to fall to compelling levels.

To help you determine if the company you're looking at is a first-class operation you'd be proud to have in your portfolio, here are five hallmarks of great companies:

1. Powerful brands
Think of well-known brand names in the United States or, better yet, around the world. Coca-Cola (NYSE:KO), Intel (NASDAQ:INTC), and Nokia (NYSE:NOK) are all among the top 10 brands in the world, as ranked by Interbrand. This kind of popular recognition can give these companies a leg up in their industries.

2. Significant products or services
Look for a company that's selling its customers something they really need or really want. Pharmaceutical companies such as Eli Lilly (NYSE:LLY), for example, manufacture products that people will buy whether they're flush with funds or strapped for cash. (If you're fighting diabetes, for example, you're probably not going to forgo taking your Humulin in order to save a few bucks.) Firms such as the aforementioned Coca-Cola and Burger King (NYSE:BKC) offer consumers products they love and will purchase over and over again.

3. Consistent, reliable earnings and sales growth -- and robust margins
Great companies grow steadily and find ways to get more and more of their revenue to the bottom line.

4. Strong leadership
This is in many ways a qualitative factor, but that doesn't mean you can't ferret out some useful impressions and information. There are some tricks to learn from articles such as Identifying Effective Management and Investigative Investing.

5. A lasting competitive advantage
Think of Disney (NYSE:DIS), for example. Other companies can produce animated films and movies for children, but when parents have a choice, a Disney film will get extra consideration just because of its name. When kids clamor to go to a theme park, Disney parks will command more attention and begging than something like ActionFun Park, which has few established associations. (I just made that park up.)

And then there's price ...
Once you've identified a great company, you may be tempted to rush out and buy shares at any price. Don't. High-quality companies often trade at premium prices, and paying too much for a stock will hurt your returns. But if you're patient, you'll likely find one or more on sale every now and then. Some very successful firms trading at some not-so-high prices lately include Coca-Cola and Wal-Mart (NYSE:WMT). Coke's recent price-to-earnings (P/E) ratio, around 21, is well below its historic average, which has been in the 30s or higher for most of the past decade. Similarly, Wal-Mart's P/E of around 19 is considerably lower than the 20s and 30s it's been in for most of the past decade.

Great companies at good prices. That's a recipe that can help you beat the market for decades, and it happens to be a good way to summarize the strategies that Fool co-founders David and Tom Gardner employ in their Motley Fool Stock Advisor investing service. And they're having some success. To date, their picks are beating the S&P 500 by more than 40 percentage points.

I encourage you to take a look at David and Tom's free report, "The Motley Fool's 2 Top Picks," which gives you two new stock ideas and further insight into their investing strategies, at no cost to you. Click here to access the report.

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This article was originally published Sept. 15, 2006. It has been updated.

Selena Maranjian owns shares of Coca-Cola and Wal-Mart and enjoys eating Whoppers Jr. at Burger King. For more about Selena, view her bio and her profile. Wal-Mart, Coca-Cola, and Intel are Motley Fool Inside Value picks. Disney is a Stock Advisor choice. Eli Lilly is an Income Investor selection. The Motley Fool isFools writing for Fools.