Several things that can be done on facebook to clean out a bunch of crap and be safer:
1) have a "personal" account (for family & "real" friends only)
2) a "fun" account (to surf the fun stuff without choking the personal account); this is where I subscribe to a lot of model groups, sci-fi groups, fan stuff, etc.
3) a "business" account to strictly conduct business such as what Marc was indicating; DO NOT express controversial opinions here not if you want to have a thriving business; keep it professional
4) don't invite everyone and his brother to be your friend for your "personal" account (sorry but no-one needs 2000 friends)
5) don't invite anyone other than your "personal" account to be your friend on your "fun" account, this leaves you the option to post to your "personal" account if you find anything cool you want to share. Use the "fun" account strictly for looking at the fun stuff without "offending" family or friends.
6) If you have a family member or friend get over zealous or offensive you can keep them as a friend but unfollow them.
7) Here is the tough one - on controversial hot topics refrain from comment when you can, chances no one is going to change their mind no matter how sound the argument may be.

Consider facebook is nothing more than a virtual bulletin board. Do not post anything on there that can come back to haunt you, no matter how secure you may think it is. Marriages, businesses, careers, even lives have been ruined because careless and thoughtless posting on there.
9) Do NOT post things like "enjoying" my Margarita in Mexico City. First most people could care less that you are enjoying a Margarita and second you just told someone you are not home, come clean out your house. You can share photos to those who care after you get back.
10) Be cautious posting family photos and information; this can fall into the wrong hands and become a really bad day.
11) Clean out your Internet History before and after you get on Facebook. It has tracking cookies and God knows what else. Ever wonder how they you were looking at an Star Wars DVD or RC Airplane?
12) And finally remember just because you are paranoid does not mean the world is not out to get you. LOL