I have never done this myself, but I have a friend that sells his photos online. He has his own site, but he also posts on other sites as well to gain followers and traffic to his site. I think he started off selling on another site similar to Flicker, but there are many different sites out there that you can sell your photos on to get started.
After you get your work out there, then you can put them on your own site. He makes a full time income from selling his photos and he makes three times more than what I make, he lives in a very ritzy part of California near the beach.