I'd like to share some of my experiences in a hard task: learning Android. You should consider my starting point. (see About) My main tools at this time were: CAD, oscilloscope, Eclipse.
The main Milestones:
In the beginning: Eclipse. Now Android-Studio with two separate installations : stable and canary, both on Windows 7 and Ubuntu.
Devices: from Nexus One, Galaxy Nexus, N5, N7, N9 to Lenovo Phab2Pro (Tango !)
To start learning, in self-study, everyone need _THE_BOOK(S)_,
Searching Amazon for books about Android, one get list with countless titles.
I have started with: "Hello, Android" by Ed Burnette, Pragmatic
easy and fun to read
To go on with learning, effective, best book in my opinion: BigNerdRanch
very detailed with best tutorials from zero to pro, reference too
Very good books, from official Android Advocate:
Professional Android 4 Development by Reto Mayer
Next level, not for the beginners, "The Must Read", specially Examples:
For a software developer as me, to understand the nuances of design:
For mobile (on the go) development of Android (mobile workstation, IDE) ,:
Ultimate Android by Mike Riley
To understand AOSP, structure, content:
To work with sensors:
I'll recomend both books from Onur Cinar:
The list of some Bibles for every software developer:
it's only one problem TIME...
The Android Bibel: google android , training, reference,
equal important: Stackoverflow,
Udacity fantastic courses
UX, specially mobile:
Android Backstage, Fragmented, ...
Blogs and G+ from gurus.
Last but not least Android-weekly