^ This! Also, the most valuable part of investing is asset allocation, i.e. how you split your money up between stocks and bonds (and optionally real estate). Take your age, and put that percentage of your money into bonds (if you're 30, put 30% of your money in bonds). Bonds are safer and you want to conserve your money as you age. Make sure the bond maturity dates aren't later than you're going to need them. Reallocate your assets every 18 months so that your diversification continues to match your age. Read fund prospectuses to learn about the fees and expenses they incur -- this is boring, but the lower the fees and expenses the better your portfolio will perform.