My question involves business law in the state of: Florida

I'm trying to start a local computer repair business. I intend to do the repairs on site, or, at the customer's residence. I have a business name all picked out that I want to use. What all do I need to do to make sure that I'm doing this legitimately and legally?

Edit: A bit more info.

I don't have an office. I work out of my car basically. Just drive to a customers house, fix their stuff, get paid and go. I just want to fix computers and get paid for it. I want to do so under a ficticious name. The problems is that all the legal side of it is just confusing to me. I assume that I have to be licensed to do business and such, but I can't find a simple process to get the license. I also want to be able to legally put out fliers and business cards and advertise my services. I'm assuming that what I want is a sole proprietorship.