Exchange-traded funds offer a convenient way to invest in sectors or niches that interest you. If you'd like to add some international dividend-paying stocks to your portfolio but don't have the time or expertise to hand-pick a few, the iShares Dow Jones International Select Div ETF (NYSEMKT:IDV) could save you a lot of trouble. Instead of trying to figure out which companies will perform best, you can use this ETF to invest in lots of them simultaneously.

The basics
ETFs often sport lower expense ratios than their mutual fund cousins. The iShares ETF's expense ratio -- its annual fee -- is a relatively low 0.50% -- and it recently yielded more than 5%!

This ETF has performed  well, outstripping the MSCI EAFE index over the past three and five years. As with most investments, of course, we can't expect outstanding performances in every quarter or year. Investors with conviction need to wait for their holdings to deliver.

Why international companies?
It's a smart idea to diversify your holdings not only by market size and industry but also geographically. If the U.S. economy stalls or slides, other economies may still be performing well and could help offset losses in your portfolio. Dividend-paying companies offer an extra bonus, as dividends can be quite powerful. Internationally reaped ones can be a little more complicated than domestic ones, though.

More than a handful of international dividend payers had strong performances over the past year. France-based oil giant Total S.A. (NYSE:TOT) jumped 23%, and yields 4.3%. It's ambitious, taking on some riskier projects such as offshore Nigerian fields as well as shale drilling in Europe. Like its peers, though, Total is facing rising costs and shrinking margins.

Seadrill (NYSE:SDRL) gained 21% and yields about 8.4%. The deepwater drilling specialist has been executing well and dominating its realm, in part via aggressive financing and high debt. Still, its backlog was recently $19 billion, and one of its subsidiaries has snagged a $2.7 billion eight-year contract with Brazil. Seadrill's fleet is more modern than those of its peers, and it's also expanding its fleet. Bears don't like it paying out more than it earns, in dividends, worrying about dividend sustainability.

Italy-based oil giant ENI SpA (NYSE:E) advanced 12% and yields 5.3%. The company suffered serious disruption by political unrest in Libya a few years ago, and is now facing unrest in Egypt, as are Royal Dutch Shell (NYSE:RDS.A) and others. ENI is active in Syria as well. ENI sports double-digit revenue and earnings growth, with revenue growth accelerating in recent years. It has been moving into natural gas in recent years.

Other companies didn't do as well last year, but could see their fortunes change in the coming years. Royal Dutch Shell gained just 2% and yields 4.7%. The company has suspended its drilling in Alaskan seas, after investing billions in the initiative. The company has more than $30 billion invested in liquefied natural gas (LNG) projects in Australia, but those have been cost overruns and delays there. Meanwhile, Shell has a new CEO, promoted from within. As with most companies, there are things to like and dislike about Shell -- with bulls pointing to its hefty dividend and relatively low valuation.

The big picture
A well-chosen ETF can grant you instant diversification across any industry or group of companies -- and make investing in and profiting from it that much easier.