Look and Feel guidelines
Useful tools from Sun include:
There is a widespread tendency for GUI code - in particular initialization code - to be implemented with very long methods. This is probably a bad idea, for the same reason that all excessively long methods are a bad idea - they are harder to understand and maintain.
Fields should be created only if necessary. If a particular element is created, wired into the GUI, and then no longer referenced anywhere else in the class, then it should probably not exist as a field, but rather as a simple local variable. This style will allow the more important GUI elements (fields) to stand out from the less important ones (local variables).