The key to getting the biggest bang for your buck is asset allocation. The right mix of stocks, funds, bonds, cash and other investments should balance risk and return in a portfolio.

And Americans are either doing a great job at monitoring their retirement accounts or really falling asleep on the job, depending on who you ask.

Many 401(k) investors are following the common wisdom of harnessing higher-risk investments earlier in their careers and transitioning to less risky options as they get closer to retirement, according to a recent study by the Employee Benefit Research Institute.

"What's interesting to note is how differently individuals in these plans choose to allocate their assets," says Dallas Salisbury, president of the institute. "The actual numbers end up fitting with what most advisers say people should be doing."

But another recent study showed that at least some IRA holders were not rebalancing their portfolios on a regular basis. When John Hancock Financial Services surveyed account holders in 2004, more than half -- 58 percent -- said they had a specific plan for their asset mix, says Wayne Gates, the company's vice president of fixed products. And 90 percent of that group said they were at or near their target. But 59 percent of those with a specific plan also admitted they had not done anything to rebalance their portfolios in the past year.

When asked how much time each month they spend monitoring their accounts, IRA holders averaged about 35 to 40 minutes. And that's not nearly enough, says Gates.

"The fact that they are investing or saving is very, very important -- that's No. 1," he says. "But No. 2 is asset allocation and rebalancing."

Check your money often
Part of the secret of saving for your own retirement is getting into the habit of regularly looking after your own financial interests.

Even if you have a portfolio of managed mutual funds, you still want to check in every so often and see what the fund manager is doing with it. Is the fund manager trading stocks within the fund that are costing you money? Or is the manager making decisions that put your portfolio in a higher risk category than you'd like?

Maria Scott, editor of the American Association of Individual Investors Journal, says you should review the progress of your mutual funds every quarter.

"Make sure the manager is managing the fund as you expected. If it diverges from your original goal, find out why the manager has invested in different stocks. One clue to the fact it's changed is comparing the performance of a mutual fund to an index that covers the category you think best represents what that fund should be doing, such as a small-cap index."