If anyone I knew were thinking of turning pro, the first place I'd send them would be Strobist. Not only would you learn a lot, but you'd get a pretty good idea of what kinds of problems you'd get to deal with as a pro. Right now, for instance, there's still time to get your own answers in for the devilishly puzzling flavored vodka quiz, before David lets you turn to the back of the book.
As I always say—and you can quote me—professional photography is 70% marketing and 90% lighting. And Strobist is an excellent place to absorb a lot of information about the latter relatively painlessly.
Posted by: MIKE JOHNSTON