Compatibility isn't much of an issue unless you are doing something low level with the NDK, or are using an API that has changed significantly between versions

Compatibility isn't much of an issue unless you are doing something low level with the NDK, or are using an API that has changed significantly between versions (most are fairly stable). Otherwise just follow the recommendations from the Android team for different screen sizes, etc. I haven't released my app yet and it's going to be free initially anyway, so I don't have any direct observations on revenue.