I would like to clean up some files etc. using Cleanup and Uninstall etc.

Whenever I start deleting preferences etc. I seem to delete something I wanted. I know I can make copies etc. and retrieve anything I should not have tossed, but is there an easier way? It would be great if there was a list of what should be saved vs. tossed (with preferences, files etc.)but I think this is hoping for too much... I would be happy with a list of developers and there abbreviations. Any ideas?