Invest less at the end of the month. Brokers tend to push stocks at the end of the month in an effort to match or surpass their previous month's sales.

Avoid greed and fear. These are the investor's Achilles heels. Keeping all your money in the bank earning 3% interest is just as foolish as dumping your entire savings into the market thinking you'll make a quick buck.

Invest in vanity. Buy stocks in high-profile companies whose products are designed to make you feel good and look good.

Give a cold shoulder to cold callers. Never invest in anything based on a phone call from someone you don't know or whose office is a post office box.

Sell before the holidays. Stock prices tend to rise on the last trading day before major holidays.

Always leave a sinking ship. There's no virtue in hanging on to losers. And stocks don't have feelings.

The higher the yield, the higher the risk. A high yield is designed to attract investors. An outrageously high yield attracts fools.