Append: Sex-ed article.

I think this was the source that I learned the most from.

Presenting, The Yiffy Guide to Safer Sex. PDF, free, re-printable, and not my own link, 'cause I'm lazy like that.

[ link | http://www.pilot.furtopia.org/Text/YiffyGuide.pdf ]

Not worksafe, 'cause there's pictures.