I was reminded of this recently, and thought it might be informative to include it here. Unfortunately it’s not Freely licensed, but the tips in the guide are insanely useful. They were compiled by photocamel.com user Benji. I believe they were originally this series of posts in their forum:
http://photocamel.com/forum/tutorials/16516-rules-good-portraiture.html
Someone apparently collected the posts into a simple document here:
http://www.kel.cc/downloads/Benji_RulesOfPortraiture.pdf
I wanted to mirror the document, but I’m not sure if it’s kosher without the approval/release of the original author. If anyone happens to have an account there or knows Benji - please ask him if we could re-publish his posts.