Like pro athletes, investors are always looking for that extra edge to juice their returns. Some turn to momentum trading or complex hedging schemes, while others put themselves in precarious margin positions.

In an effort to pick stocks on the upswing, investors often look at buybacks and insider buying as positive signals. The logic is noble: Put faith in those who have faith in themselves. But there's mounting evidence that these signals don't set investors up for any particular success.

The lure of the big buyback
Why have corporations been big on buybacks lately? For one thing, a few years of solid economic growth have left them flush with cash, even as the recent economic conditions have decimated their stock prices. And some big players are set to take advantage of the recent turmoil -- Dell (NASDAQ:DELL) has a $10 billion authorization to pick up a stock slashed nearly 60% in the past three months, and Schlumberger now has an $8 billion repurchase plan that was approved earlier this year.

These announcements by themselves may give investors the impression that any company doing a buyback is a strong business with cheap shares, but a recent study from Standard & Poor's doesn't back that up. It said, "While some S&P 500 companies have used buybacks judiciously, repurchasing at discounts to recent share prices, most companies have been too enthusiastic with their stock-buyback programs and have not increased shareholder value." And some have had to rethink their repurchase enthusiasm and suspend their programs to conserve cash, as Target (NYSE:TGT) has recently done.

So repurchase plans by themselves don't signal that outperformance is on the way. The same goes for insider purchases, according to a recent paper from two German finance professors, who argued that "insider trades do not reveal exploitable information." As evidence, consider that numerous insiders at Thornburg Mortgage were fronting millions to buy significant amounts of stock in 2007 -- stock that is now essentially worthless.

A better way
The key to earning superior returns is not timing the market, but rather spending time in the market -- particularly if you hold great, dividend-paying companies over the long haul.

For example, let's say that an investor bought $10,000 worth of a stable, dividend-paying stock, then held it for 25 years. We'll assume 8% annual appreciation in shares, plus a constant 3.25% dividend yield paid at the end of each year. If you took those dividends each year and spent them, your 8% appreciation would still leave you with $68,485 after 25 years. Very nice.

But reinvesting that annual dividend could more than double those returns. With dividends reinvested in the example above, your total after a quarter-century would exceed $140,000.

The Foolish takeaway
Eager to turn this example into reality? There are plenty of fundamentally strong public companies paying consistent dividends that significantly boost returns over time. Consider these companies that combine an attractive yield and long-term return:

Company

Annualized
25-Year Return
*

Current Yield

Colgate-Palmolive (NYSE:CL)

18.6%

2.5%

Duke Energy (NYSE:DUK)

10.8%

6%

BP (NYSE:BP)

9.6%

7.3%

Automatic Data Processing (NASDAQ:ADP)

13.9%

3.5%

Deere (NYSE:DE)

11.9%

3.4%

*Returns from Yahoo! Finance, including spinoffs and dividends reinvested.

James Early and Andy Cross, our analysts at Motley Fool Income Investor, regularly put hundreds of high-yielding companies under their microscope and recommend two each month. To learn more about all the selections, and how to double your returns through dividends, check out a no-obligation 30-day free trial.

This article was originally published  March 20, 2008. It has been updated.

Fool contributor Dave Mock still rejoices over change found in the sofa. He owns shares of Johnson & Johnson. Duke Energy is a Motley Fool Income Investor pick. Dell is an Inside Value recommendation. The Fool's disclosure policy may be easy to overlook today, but in time will balloon larger than life itself.