Those are all the files you create and keep, programs, settings etc.
best way I know is just to create DIRECTORY that will be backuped and exclude most stuff(especially desktop,userdir, temp folders etc).
it will be a pain IF needed, but will keep you from backuping same file ~30 times when you will edit single coma and save.
I turned it off completely, I have recovery partitions, important stuff in cloud and monthly whole disc images.