Check out Ubuntu Bugmaster Brian Murray on the Fresh Ubuntu podcast! He explains the life cycle of a bug and how to file useful reports. Oh, and he’s on youtube as well 
The point he made about using the ‘Report a bug’ menu entry is worth repeating: It’s the preferred method for filing a bug on a GUI application. Please file bugs this way:
For non-gui applications there is also a command line interface in Apport for filing bugs: apport-cli -f -p PACKAGE See the Reporting Bugs help page for details.