6. Failing to achieve true diversification
ETFs are basically diversified investments, but don't be swayed into believing that investing in just one of them will automatically allow you to have true diversification. Some are diversified, but in only one asset class asset class--they're focused solely on the energy or precious metals space, for example. Make sure that the totality of your ETF investments has a broad base of investments in commodities, stocks, bonds, and possibly international funds. That's the best way to ensure true diversification.
As with just about anything when it comes to your money, research and homework are the two main keys. Use ETFs to your advantage, and be make sure you avoid the above mistakes. When you're lying comfortably on a beach in Ft. Lauderdale once you've called it a career, you'll be glad you did.
What other mistakes should be avoided when investing in ETFs? Let us know if you have any other tips--leave a comment below.