Top Questions Before Buying a Stock:

No. 1: What Does the Company Do?

Go ahead and laugh. Warren Buffet famously says he doesn't invest in what he doesn't understand; if the greatest investor of the past 60 years is brave enough to acknowledge that he doesn't understand all companies, there must be some wisdom contained within. This first basic question is a simple one, but that doesn't mean it's easy. To answer the question, there are plenty of places to look, including the company's Web site.

No. 2: Is the Company Profitable?

This is also a simple question, which can be made more complicated by all sorts of variations on a company's earnings. Investors can read the quarterly and annual earnings reports to check out how much net income the company reported, in dollars and in per-share earnings. Tyco and the slew of past scandals drove home the notion that reported earnings aren't always kosher, but later down in this column we'll address ways to mine for red flags in earnings.

No. 3: What Is the Company's Earnings History and Outlook?

A quick scan of older news stories and the company's past quarterly statements help answer this question. Does the company have a history of steady earnings growth? Are earnings volatile? Remember, all trees don't grow to heaven: If the company is a maturing tech company can it sustain the heady growth of its days as a spry, young growth company?

NEW YORK (by TheStreet) -- It may seem like a given that you should do your homework before plunking down your hard-earned cash on a company's stock -- but many people don't, according to a study.

"There are some investors who simply don't carefully weigh their stock-investment decisions," said Brad Barber, University of California Davis professor and co-author of the study All That Glitters: The Effect of Attention and News on the Buying Behavior of Individual and Institutional Investors. "Individuals are heavy buyers of stocks that are in the news -- that is true of good and bad news," he said.

As stock market crashes have taught us, a carefree investing style doesn't work forever; in fact, its success usually comes to an abrupt end. It would behoove investors to relearn that painful lesson before the next crash. With that in mind, this column offers 10 questions investors should answer before buying a stock.

Some of the questions may see pedestrian to more seasoned investors. If so, humor us a little with our refresher course. And, of course, knowing all the answers doesn't guarantee a winning stock -- in fact, nothing does. But over the long haul, it will make one a better, more well-informed investor.Investors in all stocks need to be able to answer this question, although run-and-gun investors might not need to answer it and that is fine: I don't have any useful advice on that investing style. But serious-minded, long-term investors need to answer the 10 questions above before buying a stock. In truth, these aren't the only questions an investor needs to answer; they are just a starting point. There are dozens of questions that are specific to the company and the industry that shouldn't go unanswered. Lastly, the questions need to be revisited after the stock is purchased to make sure the answers still hold up. (by TheStreet)