Some Debugging Tips
Enabling the console
You may want to run Client.pyw with the console instead of with the windows subsystem. You can do this by simply renaming it Client.py, you'll then be able to see output in the console window.
The client won't launch and exits immediately!
If you can't get the game to launch, you can drop to a command shell and use C:\Python25\python.exe Client.pyw to see whatever exception is being printed out. In practice, this is pretty rare...
Editing/Client/Embedded World Server testing
Check the console.log file in your source installation for possible errors.
Check the file log_MinionsOfMirth.txt (we still have a few legacy filenames) which is a folder up from your source installation.
Testing code on a Zone Cluster
If you are running into a problem with your Zone Cluster, check the log_ZoneCluster0.txt, log_ZoneCluster1.txt, etc
If you are using Eclipse with PyDev?, it has a very nice integrated debugger. You can set breakpoints, analyze variables, etc.