Hi Miguel,
I've been a Windows (first C/C++ and then C#) developer for more years than I care to remember. I decided to get into Android development (coming from a Windows Forms background) a few years ago. All I did was read these 2 O'Reilly Press books:
While they're a bit dated by today's standards, they are still very pertinent to the subject and are extremely well written (IMHO).
I develop native Android apps in my favorite language (C#) using Visual Studio and Xamarin. I love the dev environment and have been very happy with my journey into Android thus far.
Hope you find this useful!
/ravi