Step 2: Get a prototype up

Just as Realtors will tell you that the three most important things when looking at a property are (1) location, (2) location, and (3) location, any entrepreneur will tell you that the three most important things when starting a company are (1) execution, (2) execution, (3) execution.

So you've got your partner, great; next stop is a prototype. I'll skip everything in between (vetting the idea, figuring out how it's gonna make money, etc.) because in today's development environment, it's easy enough to just try things out without all the up-front planning. If either you or your partner are technical, that means y'all just start coding. Yes, mockups are extraordinarily helpful, and functional requirements that go with those mockups are great too -- but don't spend ages on perfecting either as they're gonna change later regardless (again, if you've done this before you probably don't need to read this blog). As you work to put together your prototype, it may be helpful to look at other sites out there you'd like to emulate.

As I mentioned earlier, you'll probably want to develop in Ruby on Rails. For hosting, you may wish to try mediatemple. As an FYI, I used Fireworks as my graphic software and PowerPoint as my "spec writing" software.