What is the best way to learn Android app development?

Start out reading a couple of books and started making a simple app and then google.I suggest following the tutorials and guides on http://developer.android.com and just jump into it.

If you have experience with Java, then you can start by http://developer.android.com/training/index.html.
else start learning Java.
If you are student try getting some projects, thesis, ...etc in Android.
Then you expand your expertise by consulting this book "Android Application Development: Programming with the Google SDK" published by O'REILLY.

if you are looking to learn developing Android applications i think the best resource for that lynda.com online video library suitable for all levels.

http://www.vogella.com/android.html it is a good start

if(developer) { if(Java Dev){ learnAndroidDev(): }else{ learnJavaFunds(); learnAndroidDev(): } } else { learnOop(); learnJavaFunds(); learnAndroidDev(): } System.out.println("U R Welcome :D");

There is no single way to become proficient in any niche. However I'll suggest you to first understand the architecture of android on its official website and then start following some decent blogs. Last and important thing, you need to practice really hard, as nothing is easy in this world. I hope this answers your question.

Here's a good tutorial: http://mobile.tutsplus.com/tutorials/android/introduction-to-android-development/

If you are interested.
Watch these videos.
Try to download them so that you could watch again if you need.
By completeing 30-40 video you will be like a semi pro..
You would have understood the basic and everything....
http://www.youtube.com/course?list=EC2F07DBCDCC01493A