Website from where you download Android Studio contains all the information required by a developer to start Android application development from zero. I see a featured article on their website '11 Weeks of Android' to learn all the new things, planned and scheduled
1. Go through documentation and try. General best practices and tools to be used by developer are mentioned here: Android Developers
2. If you like to learn looking at existing projects, believe GitHub
] repositories would help. Even CodeProject resources
About making money, there are options like In-App purchases. An answer here by one of the CP member details them: Selling items in Android Game
Lastly, learn and share. That would help you overall across. Happy Learning!