[danjl]

This approach has worked for me, and many others. Read the Lean Startup for the general approach, and The Mom Test to learn how to talk to prospective customers. The main point is that you need to talk to customers and work with them throughout the process.

[Karrot_Kream]

I never read over the Mom Test but this thread has so many recs for it. Definitely moving it up in my list.