Android development:
- read the official documentation
- implement the logic in your app using what you learned
- find out that at least one method is always deprecated
- read the updated API and, as always, check out your loyal friend Stack Overflow.

Old method is deprecated, new method isn't supported by the chosen API level...

The big issue is when they deprecate stuff after you finish development. Sometimes you start getting "this is marked for deprecation" on logcat for a while. But sometimes it's just out of the blue (Gallery, I'm looking at you). Good thing is that if you try to use something when it's already deprecated, Android Studio will warn you, and some times it will even tell you what is used to replace it. If you get a deprecated sign, you first make a search for AppCompat+the thing to check if you have your work done already. If not, enter ugly VERSION.SDK_INT ifs.