The opportunity being presented in the stock market right now is a once in a lifetime event. You will not see this again unless you have the longevity gene.
Any extra money not needed for living should be carefully invested in today's market. By carefully, I mean in small enough amounts so you can keep on buying throughout this downturn - and in only the best of the best companies (which pay dividends).
Mutual Fund companies can take most of the guesswork out of it for you since they are managed by professional, full time people. Choose the Mutual Fund Company with the lowest fees because large fees will eat away at the money you can invest (one such company is Vanguard - www.vanguard.com).
You can also invest directly in stocks by getting involved with a company's DRIP (Dividend Reinvestment Plan) which you can find on the Internet. Companies stock purchases are handled by companies such as Computershare (www.computershare.com) where you can find many DRIP plans. You invest in these either whenever you want by filling out the coupon and sending it in, or by periodic automatic investing.
It has been proven that investing over time (once a week or once a month-called dollar cost investing) is the best way to maximize your earnings because it does not allow you to try to time the market - which does not work over the long run. You will end up buying the low priced stock more often using dollar cost investing because you won't be trying to wait it out to see if the price goes lower. You also won't have to spend the time tracking the stock price every day so you can enjoy your life more.
Investing in stocks can also be done through a brokerage, where you go online and buy through the brokerage web site. First you have to have money in an account (usually a money market fund which earns dividends-kind of like interest). Then when you make buys, the money comes out of this account. Any earnings from the stocks are paid into this money account. You can track all your stock investments from the brokerage on one page.
No matter which method you use, you want any dividends or gains to get reinvested. That way your stocks will automatically grow even while you are not actively investing. For stocks, dividends are paid out four times per year. Each time you get dividends, they buy stock shares which earn more dividends at the next quarter. This snowball effect is exactly what you are looking for.
If you are not extremely close to retirement age (or if you are and have extra money lying around getting 2% in a CD). You should be buying stocks while they are ON SALE. If you are in the market - HOLD ON - if you have selected the best of the best companies which pay dividends, you will be buying shares on sale with every quarterly dividend.