Actionscript OOP Design

I’ve started getting into ActionScript 3 lately and its been a fun learning curve. The one thing I seem to be struggling with is laying out my code into multiple classes. I’ve been learning it from the AS3 Cookbook and from http://livedocs.adobe.com.

The one thing these seem not to explain is how is best to structure you code across multiple .as files. Does anyone have any handy tips? or is it best to start looking into OOP Design for this?

edit

Could anyone recommend any good books for OOP design, preferably geared towards AS3?

Cheers

Dave