You've already read about how to turn me on, and I do so appreciate your willingness to learn. But I'm pretty sure you'd rather be getting yourselves off.
[$10.85, Amazon]
I finally got around to reading Jamye Waxman's Getting Off, and aside from helping me choose a new lube, and teaching me the correct way to clean all my vibes, the book was a wealth of information for any level of masturbator, even going so far as to offer techniques for the first-time finger banger.
I've read a lot about sex (you should see my bookshelf). No other sex manual has made me want to run out and purchase 5,000 more copies so that I can walk the streets, dispensing them like free condoms in a jill-off crusade. Seriously.