Not to be a naysayer, but not all apps are stuff people _want_ because they aren't exactly solving their problems (or satisfying them). So IMO, the first step is having an honest conversation with yourself. Next would be to talk to your few users & friends, to try to find out if they like the app and if they would recommend it to a friend or two. As PG Says, "if you make something users love enough to tell their friends, you grow exponentially, and that will convince any investor"[1]. Note that, 'Convince any investor' here is proof of growth.

[1] http://paulgraham.com/good.html

If you haven't read any of these, you should check them out. http://paulgraham.com/ds.html http://paulgraham.com/growth.html