If you're investing on a personal basis you'd need to put in upwards of at least £10,000 ($12,000) to make any money and for your time to be worth it. I'm planning to invest but only when the market tanks again in a 2008/2009 like scenario and when I can be reasonably sure stocks have reached rock bottom. Taking into account brokerage fees and so on you can double or triple your money if you time it right in such a situation and get in on the rebound.