This article mentions the six things you need to do to make your mobile app successful. It notes that you need to do these before you actually launch the app, and that they may not need a large amount of money to start. The first thing you should do is to make your press kit pop, next make sure you keywords are well chosen, build a microsite, create a teaser campaign, keep content fresh, and build hype.

Read the full article here:
Mobile App Marketing 101: So You’ve Got an App Idea, Now What?