Noobie

Helllo, and greatings to all...
new to all this.
have installed cyanogenmod nightly rom on z1 and it is rooted too. but when i was doing initial backup in CWM it backed up to internal storage first, i then backed it up to sd card.
However, what if anything should i keep in the internal storage?
i may have put stuff in ther and want a nice clean machine.
am presently doing titanium backup, but also find that i couldn't change the backup location to the sd card either!!
any help would be greatly appreciated.
Leo

p.s.
you may have to walk me through doing a directory list of internals.