Buy low, sell high

A near no-brainer. The challenge comes in determining when the stock is at its highest and when it is at its lowest. Many investors panic and bail out when a stock takes a brief tumble, only to be dismayed when the price rebounds.

Invest long

Only those with true talent and determination make money by buying and selling stocks in the short term (i.e. day trading); very few casual investors fall into this category. Historically, the market as a whole has been steadily rising; in spite of the occasional peaks and valleys which are nearly impossible for a layperson to predict. It's best to hang onto stocks for 5 to 10 years or more.

Avoid fees

Another plus of investing long is avoiding transaction fees. Each time you buy or sell shares, you have to pay fees to your broker. Online trading is also a good route, as fees and minimum investments are usually lower. Diversify! The old adage about eggs and baskets holds true for your money and stocks. Hedging your bets reduces your risk and ensures that you won't be left empty-handed if your one surefire stock turns out to be not-so-hot. A good way to diversify is to invest in mutual funds or index funds, which automatically spread your investment over several different stocks.

Hire a Professional

Although there is a veritable smorgasbord of stock tips and advice available on the Web, TV and in bookstores; hiring a professional financial advisor affords you peace of mind and most likely: better returns. No matter how much of your free time you devote to researching stocks, it is doubtful that you'll obtain as much expertise as someone who invests full time. In most cases, the increased profits you'll reap by putting your money in good hands ends up covering the fees that an advisor charges. While the stock market may seem daunting and volatile, subject to the whimsy of the global economy and other inscrutable factors; following a few basic guidelines will help protect your investment in the long run.