Before you start any online business, check it out and research. A lot of them are scams or give misleading information. For example, there may be hidden fees or false hopes of making millions of dollars. So far, the only things that worked for me was selling items on EBay and writing for different sites such as AC and hubpages, and I don't make much with either of these.
I usually make $30 a month on AC and just a few dollars on the others. It's something to give me some spending money.