There are some really good books on Android development I suggest Professional Android Development Android essentials Android - A programmers guide Any one of these books will get you started. My personal preference is the first book (all links lead to Amazon, you can find cheaper deals elsewhere if you wish) You can always head over to http://code.google.com for online support and help
Do you already know programming in general (preferably OO) and specifically Java? That would be the first place to start if you don't already have that experience.
I picked up a good book the other day called "Hello, Android: Introducing Google's Mobile Development Platform" by Ed Burnette. I'd say this book is for beginners and advanced users learning Android for the first time. The thing I look for in a good book is practical examples. And this book has some good ones. It goes from UI layout (User Interface), 2D graphics, Audio/Video, Data storage, Internet, GPS, SQL (database managment), and even OpenGL 3D. It dosn't get too deep into anyone one subject but that keeps the book light and easy to understand. And once you've compleated the book you'll know enough to be able to look things up via google's Android database and understand them.
If anyone here does know a decent amount, contributing to the Android Wiki would be greatly appreciated and would help people out in the future