To prepare for implementing the Chimera2 UI, I read through various materials to get me up to speed on wxPython programming. I found these useful:
The author's first language isn't English, but the few places where that shows through are still pretty clear. Covers a lot of ground pretty thoroughly, but doesn't cover everything. For instance, neither the Grid class (principal widget for MAV2) nor the AUI class (the class that implements all the fancy features I demoed) are covered. But very good for getting a grip on basic concepts like how to layout widgets and handle events and so forth.
An incomplete tutorial, but the parts that are complete are thorough and clear. Covers less ground than the preceding tutorial, but takes a slightly different tack on some explanations, which might make some things clearer -- particularly if you read both.
There are also three books, which have their strengths and weaknesses which you can read about in their reviews:
wxPython 2.8 Application Development Cookbook: Cody Precord: 9781849511780: Amazon.com: Books
Wxpython in Action: Noel Rappin, Robin Dunn: 9781932394627: Amazon.com: Books
I personally wouldn't want any of these books myself, since none of them are reference manuals which is principally what I use books for. Also, none of them cover wxPython 3.