Before buying a stock, always check up on the company first. Base your decision not only on past results but also on the company's prospects (new products, competition, etc) and the industry. Invest only in the companies you 'understand'. If you are not sure how a company makes money, be cautious. Make sure the investment fits into your long-term strategy. Diversify: don't buy only one stock; buy several from different companies and sectors. Don't get too greedy; you can sell and buy again. Don't invest all your money: keep some for emergencies. Mutual funds may be an easier way to start: the fund will choose the stocks for you and you can invest smaller amounts.