The market's now full of exciting dividend yields. Among dividend-paying companies listed on U.S. stock exchanges, more than 1,300 -- over 40% of the total -- recently sported yields greater than 5%.

But you often can't trustunusually high yields. In a market like this, littered with dividend reductions galore (and more dividend cuts on the way), it can sometimes be hard to predict whether a company's future earnings will support future dividend payments. And if they won't, well, those high dividends are likely to end up on the cutting-room floor.

Even the long-term dividend payers aren't immune. Wells Fargo , Dow Chemical , Motorola , General Electric (NYSE: GE), and International Paper have all cut their dividends lately -- even though all of them have long been viewed as solid blue chips.

Don't despair, though. There are still ways to achieve high dividend yields relatively safely.

Dividends rising
Over time, stock prices increase; ideally, so do dividend payouts. But your cost basis doesn't change, no matter what else happens with the stock. Even if a company is paying out 3% compared to today's stock price, it's paying out far more, relatively speaking, to those who bought the stock for much less, many years ago.

McDonald's , for example, was recently paying out $2 a year per share in dividends. That's a 3.6% yield if you buy now, when the price is around $55. But I bought it nearly three years ago, when the price was around $37. That gives me a 5.5% yield on my cost.

If McDonald's increases its dividend by 12% per year on average, in 12 years it would be paying out nearly $8 per share, giving me a 22% yield. In just 15 years, my effective yield would be a whopping 30%! And this is all separate from whether the stock itself appreciates.

So, while the current yield on a stock might be only 2% or 3%, that's for people buying the stock right now. Those who bought it long ago at lower prices, and now get that same dividend, enjoy a higher effectiveyield. And over time, that yield can grow very high indeed.

Why it matters
Healthy, growing companies have more going for them than dividend increases. Over the long term, their share prices also tend to rise.

McDonald's, for example, has averaged 20% growth over the past five years, and its dividend has grown by an average of roughly 30% over the past five years -- even factoring in the last terrible market year.

That combination of strong stock growth and reinvested, growing dividends has made companies like Altria the best-performing stocks of the last half-century, according to Wharton professor Jeremy Siegel. That's the power of dividend growth.

While growing dividends and healthy, effective yields boost portfolios in any market, they're especially helpful in markets like this one, because solid dividend payers keep paying you no matter what the economy is doing.

Remember, though, that hard times can also make it challenging for some companies to keep paying their dividends. That's why it's always critical to choose firms that are particularly healthy and stand little chance of reducing or eliminating their dividend. (And it's also why some people are saying that now is the right time to load up on dividends.)

How to find healthy companies
To zero in on stable companies with growing dividends, look for relatively little debt and relatively robust cash piles (via the balance sheet). Also keep, an eye out for growing revenue and income, and ideally, rising profit margins. Be wary when accounts receivable or inventories are growing faster than sales.

I used those general guidelines to screen for companies with dividend yields of 2.5% or more, returns on equity of 15% or more, and price-to-earnings (P/E) ratios of 20 or less:

Company

Recent Dividend Yield

5-Year Dividend Growth

Return on equity (ROE)

P/E

Procter & Gamble (NYSE: PG)

3.1%

12%

22%

13

Nokia (NYSE: NOK)

3.3%

17%

28%

11

3M (NYSE: MMM)

2.7%

8%

26%

19

Automatic Data Processing (NYSE: ADP)

3.3%

19% Continued...