When it comes to making money with your newly acquired skills, there are many different options. Some are more exciting than others. But basically it comes down to three ways to make money as an Android developer.

1. Publish an App that is either paid or has ads in it.

2. Get a job as an Android developer, working for a company.

3. Get gigs as a freelancer and work yourself from one gig to another

I personally would start with 3. and try to build ideas I have along the way using 1. Of course, starting with 1. and using the apps you build as a reference to get more and better gigs is also an option ;)
But that is just my preference. This really depends on your personality and your current situation.

There are apparently 13 different ways to make money as an Android developer. At least that's what this article says. So check it out, if you want to learn more. 

Whichever way you choose I hope you will be successful on your journey and wish you all the best