Crave 'real' stocks?
Mutual funds and index funds are fine. But what about the regular investor who wants to own a few shares of "real" stock?

Do it, but stick to amounts you can afford to lose, say several experts.

"I have people who want to have a little trading account," says Miller. "So we open it up and have that trading account." But like that trip to Vegas, keep the money separate from your investments and never put up money you need, she says.

If you're the kind of person who enjoys speculating with stocks, do so with two or three stocks, maybe 5 percent to 10 percent of your portfolio, says Bogle. "But don't have fun at the expense of your retirement or your kid's college education."

What about inflation?
Worried about inflation? Join the club.

Inflation should always be a factor for investors, but it has the most impact on retirees, says Edelman. "Those receiving income from retirement notice it more than the rest of us," he says.

The solution: stay diversified, keep your portfolio growing through a portion of stock funds and consider inflation when you do your investment planning.

One possible pick for the bond side of your portfolio: Inflation-protected U.S. Treasury bonds, Bogle says. Tally up the return you're expecting on your bond investments. Then look at the return for the inflation-protected bonds (which will be inflation, plus a fixed rate of return).

When you invest in inflation-protected bonds, you're essentially betting that inflation plus the fixed rate will be higher than the rate you would get on your regular Treasury bonds, he says.

But the bottom line is that any investment is risky. With higher return investments, you risk the capital. With lower-return, safer picks, you risk losing the value of that same money to inflation.

"Even with the bulk of your money in safe investments, like CDs, you're taking a big bet," says Edelman. "Every investment has some form of risk. The only way to minimize that risk is to diversify extensively."

A portfolio dominated by bonds or bond funds could cause problems for retirees later in life, he says.

"With people living so long, having your money predominantly in bonds could create a massive loss in the value of the assets," says Edelman. "There are more losses occurring in the bond market than the stock market."

"One of the misconceptions that investors have is about risk. They think about it in one-dimensional terms: risk to principal," says Roper.

That's valid, "but it's not the primary risk factor you need to be concerned about when you're investing long-term," she says. "Investors who focus excessively on the safety of the principal face the very real risk of gravitating toward investments whose value will be eroded over time.

"Year in, year out, stock funds are the best protection against inflation," says Roper. At the same time, "it's important that people understand that stock funds are long-term investments."