unnecessary config files and dirs

[Dj YB]

Hello,
I have been dragging my home folder since fedora 10 and know that some 
problems I got are because of my configuration, few examples
in kscreenlocker all the windows are black rectangles.
akonadi requires restarts frequently to watch kaddressbook records

so I wish to get rid of unnecessary configuration files and folders in my home 
folder.
how do I start, how can I know for sure a directory is not being used for 
something.

Thanks,
YB.