[EDIT May 28, 2010: This article has been updated to reflect FaceBook's latest privacy changes.]
If you haven't already read my Lockdown or Death for Your FaceBook Profile article, here are two videos which guide you through the process of locking down a typical FaceBook account for increased privacy and user security.
Part 1: Clean Up your Profile and Remove Information
Part 2: Adjust your Privacy Settings (UPDATED)
Be advised in the videos that since this was a new "Demo" account your options may vary and your lock down process may be a little more complicated than what I have demonstrated. In which case, I suggest you look at the Gallery which details the settings you need to look at.