Themes and colors
There are nearly 3.5 million apps in the Google Play Store. That’s a lot of apps to choose from, which is good for users, but for the developers, that’s a lot of competition.
If you will publish an app, you need to polish it—even if it’s just cosmetically—so it doesn’t come across as shabby. Even if you have a killer app, you should also think about how it looks (and feels) to the user. Remember that no matter how great your code is, the user doesn’t see the code, he sees the UI.
Google has published a set of guidelines on user ...