One thing

[fred rosenberger]

If you could only tell someone ONE thing about starting programming in Android (i.e. the biggest 'gotcha'), what would it be?

[Nidhi Sar]

Permissions, Permissions, Permissions....

Can't tell you how many times I've been bitten by it. If you are lucky the logcat will give you the reason, but more often than not, code would simple fail without the right permissions in the manifest file.

[Peter Johnson]

+1 to Nidhi's comment. And the worst part about many examples and tutorials (including the SDK itself) is that they neglect to tell you which permissions are required to get the code to work.

The next thing is to understand layouts, activities, intents and adapters. And understand the activity lifecycle.