As the past couple years have shown, U.S. equities are once again a prime source of attractive returns. But they’re not the only — or necessarily the best — source.

Like many market watchers, I believe the highest long-term returns are to be had in developing countries such as India and China, and especially in frontier markets like Singapore, Indonesia, Columbia, Egypt, Nigeria and others. I consider substantial emerging-markets exposure vital for any investor who wants strong returns.

But what if you can barely stomach the turbulent U.S. market, let alone the sickening volatility and extended downturns often seen in emerging markets? Should you just forget the latter and accept whatever domestic-focused stocks manage to deliver?

Not at all. To benefit from emerging markets while minimizing risk, you should invest in firms that are not only located and do a lot of business in developed countries, but also generate substantial revenue in developing markets. It’s also smart to buy the stocks of companies in the most advanced emerging economies.

Depending on the company, stocks like these could return double or even triple digits over time. And they’ll provide a much smoother ride.

1. Swiss pharmaceutical firm Novartis (NYSE: NVS) is one such firm. As shown by a beta (a measurement of a stock’s volatility relative to the overall market) of 0.65, it’s not terribly risky. Yet the stock could return 50% in the next few years including dividends (the yield is 3.7%), with emerging markets providing significant tailwinds.

Last year, the company’s top six emerging markets — China, Russia, Brazil, India, South Korea and Turkey — accounted for almost 10% of sales, contributing nearly $5 billion to the top line, which was a 12% gain compared with the prior year. Analysts estimate emerging markets could make up at least 15% of sales by 2015 because of management’s commitment to expansion.

The generic pharmaceuticals division, for example, which improved overall sales by 15% in 2010, owes much of its recent success to frontier markets. Last year, it grew sales by 30% in the Middle East, Turkey and Africa, 13% in the Asia-Pacific region and 13% in Central and Eastern Europe.

Alcon, an eye-care firm Novartis acquired last August and finished merging with on April 8, is another case in point. Emerging markets accounted for 20% of Alcon’s sales last year and are likely to make up at least that percentage this year.

2. Colgate-Palmolive (NYSE: CL) boasts more than 50 years of experience selling toothpaste, toothbrushes and other oral-care products in emerging markets. Currently, the company generates more than half of sales in Latin America, Asia and Africa, where its oral-care products are No.1 or 2 in market share.

Sales in those regions have lately been expanding at more than 10% annually and are likely to keep growing strongly, as consumers adopt more consistent oral-care habits. (Residents of the emerging markets served by Colgate-Palmolive typically brush their teeth less than once a day.)

Colgate-Palmolive’s stock could rise 60% to 100% by mid-decade, assuming earnings grow 12% annually, as analysts predict. However, the stock shouldn’t be very volatile, based on its beta of only 0.55. Its dividend yield is currently 3%.

3. If you can take a bit more risk, also consider Taiwan Semiconductor (NYSE: TSM), the world’s largest computer chip foundry. Although considered an emerging-market stock, with a beta of 1.01, it doesn’t act like one. And, its home country of Taiwan has advanced to the point where many believe it should be reclassified as a developed market.

Like Novartis and Colgate-Palmolive, Taiwan Semiconductor has a healthy yield (3.1%), but it’s total return could be higher, ranging from 75% to 125% in the next few years.

Chip demand, a major factor in that estimate, is expected to continue far outpacing supply for some time. Thus, analysts say sales will jump 20% this year, then an average of nearly 12% annually for the following three or four years. Earnings are forecasted to advance by around 18% annually through 2016, hence the higher return estimate.

Notably, the company has four Japanese raw material suppliers, but the recent earthquake/tsunami activity damaged them all, one seriously. This should only cause modest production delays, though, since most of those suppliers had idle capacity.

Action to Take –> Portfolios with insufficient exposure to emerging markets could generate below-average returns that hinder progress toward long-term financial goals. If you haven’t already, consider investing in companies like Novartis, Taiwan Semiconductor and Colgate-Palmolive to gain access to emerging markets in the safest way possible.

P.S. If you’re an income investor, why would you buy a stock yielding 2% when you can find one paying 26% right here? Watch this presentation for more.