This is great advice, thank you. An only extra question... being a single person means that I can't do more than one or two development projects at once, but at many times clients ask me to (and I have to tell them I can't, I'm already busy, etc). Do you think it's a problem? How do single contractors handle this?

I guess it's a lot easier if you push yourself as an independent programmer, as it's reasonable that a single guy is already busy at the time you call him... but as soon as you introduce a company name I think the expectations change. So that's an extra reason to follow your advice.