Before you invest a single dollar, get control of your debt, particularly your credit card debt. If you're like most Americans, you have a wallet full of credit cards, and you use them for virtually everything, including things you could easily pay for with cash. The best way to control your debt is to stop using credit cards for minor expenses like these, especially if you don't pay off your balances in full every month. A year's worth of interest on coffee and lunch can more than double the cost.

Replace your credit cards with a debit card and a reasonable amount of cash for the week. If you find yourself running out of cash every week, analyze your purchases before you increase your allowance. Keep one credit card in your wallet, but use it only for emergencies.

When your credit card spending is under control, you can finally attack the debt monster. There's no magic way to vanquish the debt, but you can systematically pay off all of your credit cards — and sooner than you might think. Allocate a fixed monthly amount in your budget for paying down credit cards, calculated by adding all the minimum monthly payments and adding on some extra (between 2 percent and 10 percent more is a good place to start). With the extra portion, begin paying down the credit card with the highest interest rate; lowering that balance will go a long way toward knocking out your debt. The lower the balance, the less interest will be charged, which will help you pay it down even faster. As soon as the card with the highest rate has been paid off, start tackling the next in line, and so on until all of your credit card balances have been zeroed.