First a word of warning: the stuff you'll find here is rather advanced, different people will digest it differently.
Here are some recomandations:
Try to read as much as you can about python, its true power comes from its high level, from its succinctness. The more you'll learn the less code you'll write, less code means your code will have less chances for bugs, will tend to be easier to maintain and will make your intended message easier to understand by other developers including you_from_the_future. You should read The Zen Of Python
Read about Programming Patterns especially about ModelViewController(Model-View-Controller) You don't need to reinvent the wheel, some of the smartest minds on earth put a lot of work into finding solutions to common problems, use their expertise.
Read about user interface patterns. This will help you make your applications easier to use. One of the hardest things to do as a developer is to put yourself into your user's shoes (way to many types of shoes). This kind of patterns try to help you by providing proved solutions to common GUI usability problems. Recomanded is Jenifer Tidwell's UI Patterns and Techniques
Try to follow some kind of Human-Computer Interface Guidlines. Read as much as you can about it. Here is a link to OSX HIG Even if you'll never program for OSX this stuff is still something recommended to read.
Learn to do Unit Testing. It has rather little applicability in the wxpython part BUT if you manage to split your code into Models and View-Controllers it will provide you with rock solid models (models should not have wx code in them).
Learn to do Logging. It will provide you with sanity checks and will prove invaluable when you'll try to debug your app.
- Try helping people. Even if you have only 2 days with this stuff and someone asks for help try and help him/her if you can or if you think you can. This is by far the best way to learn something.... I think it has something to do with the way in which we store information in our brain.