You can't just save money and expect to retire rich without being smart about how you invest it. For those who don't have the time, or inclination, to buy individual stocks, exchange-traded funds can be extremely useful in accumulating retirement savings, with diversified portfolios and low management costs helping to stretch your investing dollars as far as they'll go. The best ETFs combine these attractive features with solid exposure to growing markets. Depending on how you like to invest, any of the three ETFs below -- or a combination of all of them -- can help you build retirement wealth throughout your career.

1. Going with high-growth stocks

If you're like many people, maximizing the amount of growth in your portfolio is a key priority. Those who don't have a huge amount to invest have to make their investments work as hard as they can, and although being aggressive comes with added risk, the rewards can be substantial.

ETFs that focus on high-growth sectors of the market are a great way to turbocharge your portfolio's potential returns. For example, the Vanguard Information Technology ETF (NYSEMKT:VGT) owns a variety of technology stocks, and it has produced a return of more than 21% annually over the past five years, topping the S&P 500 by almost 6 percentage points per year. Yet the ETF comes with annual expenses of just 0.10%, which is a fraction of the roughly 0.50% that typical ETFs in the same category would charge.

You can find similar sector ETFs in other high-growth industries. While you might not want to put all of your money in such aggressive investments, it can be a suitable way to invest for those who are just starting out or who have extremely high risk tolerance.

Mosaic with yellow-square background on which white squares spelling ETF are superimposed.

Image source: Getty Images.

2. Counting up your investment income

Conversely, as you get closer to retirement, you have to be ready to figure out how to make your portfolio generate the cash you'll need to pay basic expenses. Many investors turn to dividend stocks for income, especially in the current market environment in which traditional fixed-income investments are paying extremely low yields that make it difficult to produce as much cash as needed.

One ETF that suits investors of all ages is the Vanguard Dividend Appreciation ETF (NYSEMKT:VIG). It gives some weight to current dividend yield in order to ensure an adequate level of income for investors right now, but its key focus is on stocks that have a history of increasing their dividend payouts over time. By giving investors dividend growth stocks, the ETF addresses the need for rising amounts of income to cover ongoing inflation in retirement costs. Overall performance has lagged the market somewhat, but reduced volatility makes many investors more comfortable, and an expense ratio of just 0.08% makes the Vanguard ETF an inexpensive way to invest.

3. Looking globally for great investments

Most retirement investors successfully find ways to get exposure to U.S. stocks. Where they tend to miss out, though, is in adding international exposure to their portfolios. That's where international stock ETFs can be helpful, as they'll focus on foreign companies, many of which have the same, or even more favorable prospects for growth, than their U.S. counterparts.

Many international ETFs give exposure to world markets, but again, cost matters. The Schwab International Multi-Cap Core ETF (NYSEMKT:SCHF) has an expense ratio of just 0.06%, but it owns a rich portfolio of stocks from key markets like Japan, the U.K., France, Germany, Canada, and Australia. Average annual returns of just over 8% over the past five years have lagged what U.S. stock markets have produced, but the prospects for economies in key overseas areas have looked better recently, offering a potential chance for them to catch up. With so many opportunities in foreign markets, U.S. companies, by themselves, can't offer every chance to cash in on worldwide growth potential.

Get moving toward a prosperous retirement

These three ideas aren't the only good ETFs in the market, but they'll give you a sense of how to come up with a strategy that works for you. The earlier you start building your retirement wealth, the easier it will be to reach your financial goals.

Dan Caplinger has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.