The first part of picking up on a big project is planning the architecture. Some tools like dependency injection and event bus are becoming standard. But a general framework for developing complex Android applications is still an open discussion.
Again, some concepts like MVP and separating use cases from the UI are getting popular. And that a good architecture should simplify testing. Alternative approaches like Flow/Mortar and RxJava are also on the spotlight.
For now, while I'm still experimenting, here's the best resources I found on Android app architectures: