Buy and hold.

What's the outlook for Yahoo or Amazon today? People who bought near the top could hold these stocks half a lifetime and never see that price again.

Investors who currently hold losers may assume they'll eventually make money because they're "holding for the long run." But if that theory always worked, buggy-whip stocks would be doing as well as Philip Morris.

Buy-and-hold investors have a good shot at making money over the long run if they buy the stock market as a whole. That means buying an index mutual fund that tracks broad market performance.

Good examples would be Vanguard's Total Market Fund or Schwab's Total Stock Market Index Fund. Both track the average price of large and smaller U.S. stocks. You get the long-run performance of the U.S. economy as a whole.

Most investors think they can buy mutual funds that will beat the market average. And indeed, in every time period, some funds succeed.

What you don't notice is that funds succeed at different times. You can't know in advance which ones will do well over your particular holding period.

Another investment truism -- forgotten in recent years -- is that careful investors "rebalance" their portfolios.

The more money you allocate to stocks, the higher the total return you can hope for but the greater your risk of loss. To control that risk, you rebalance -- meaning that you sell some high-performing investments and put the proceeds somewhere else.

As your techs and dot-coms advanced last year, your total portfolio was getting riskier. But you were doing so well, you probably didn't want to take any money off the table.