Having been in more then one business as a Sub S corp or sole proprieter my advice beyond Rob's above which was right on the point btw, would be to try and do it on the side and get a customer base and make contacts; No kidding. I've been borderline now for about 2 years to go full blown licensed business. I could see it if I was a wedding photographer or did alot of parties, but I'm not. I think it will depend on your service and what you are offering. As a landscape photographer trying to sell fine art I would say go sole proprieter just to appear as a legitimate, to say stock agencies. Beyond that it's a toss. It's a very personal decision and the services or products that your offering will have alot to do with the right decidion.