@Gropper - nice list, but do you really do all that as the "first" thing?
@* about patents. I did all of what was suggested with my first start up.From that I learned that he/she with the most money for lawyers wins. A patent will not do you any good unless you can hire a gun to enforce it. If the infringers are big, they can easily bury you despite any merits of your case. The bragging rights are nice, as are the wall plaques. So, a provisional is insurance of a sort, but it will cost you much more to make it real, and much much more to make it stick.