From Robert Geller:
How does one get attention for a mobile application and boost the odds of its success in the marketplace?
You need to first get it listed in one or more app stores and start to drive impressive download and usage stats. These show that an app has “legs” and justify a shot at media recognition and a hard launch. From there, it is a relatively shorter trip to further adoption and achieving the Holy Grail of getting your app bundled with popular devices.
It helps to develop apps for the most widely used platforms and their respective app stores. For many developers, there is only one that really counts: Apple’s. People downloaded almost twice as many apps from the Apple iOS store last year than from the Android Market, according to market research firm Ovum (although their analysts predict that Android will soon catch up and surpass Apple).
Once your app has been approved and is available in one or more app stores, there are a variety of tactics you can use to drive downloads and usage.
App Store Optimization (ASO)
It helps to find ways to maximize downloads over short periods of time. You need to leverage SEO, and consider advertising if budget allows, as outlined on the App Marketing Tips blog. On MobileDevHQ, Ian Seffernan explains ASO in more detail, including the importance of adding hooks to your app that make it easier for users to share it.
Brute Force Techniques
I am including these here with the caveat that some people – me included – consider these to be gaming the system – but there are some services that make it possible to pay for each download (e.g. Mechanical Turk).
Soft Launch / Early Media Coverage
As I said above, it is easier to get the media to take note of your app after it has already started to gain app store traction; however there are some steps you can take early on to get coverage. For example, getting your app listed on the app beta testing service TestFlight can drive early interest from reviewers.
I hope these ideas help you "get your apps in gear"!