Here's some things you can try:
Stress-testing
adb shell monkey -v -p your.package.name 500
It will help you to do some stress testing before publishing to Market.
Test your app for memory leaks. It's very easy to leak context. This post will help http://android-developers.blogspot.com/2009/01/avoiding-memory-leaks.html.
- Test your app on some device with Sense UI like EVO4G. Many things are different there.
- Take a look at this https://stackoverflow.com/questions/2094588/android-development-tips-tricks-gotchas for some more pointers about Android development