There is no substitute for the Admin Guide and lots of trial and error. I can’t stress enough that you will want a sandbox where you can easily restore back to a “clean” install. Trust me, you can easily paint yourself into a corner.
That said, you can give this presentation a look … XI 3.0 Security for Mere Mortals
Dwayne Hoffpauir 
(BOB member since 2002-09-19)