Getting to Yes: Negotiating Agreement Without Giving In - by Roger Fisher, William Ury, and Bruce Patton of the Harvard Negotiation Project.
You gotta be a phony in order to negotiate successfully. Disclose what you really want and bargain hard. It's a zero sum game after all, everything the other side wins is something you lose.
Frankly, these were some of my associations with negotiating. And many negotiations I witnessed and participated in left a bad taste in my mouth.
So I read this book, to get an edge over "the other side". I thought I would learn some tactics on the fast road to winning. But it proved me completely wrong and it even made sense. And I think my ability to negotiate has gotten better, but without any bad taste after it.
The book gives a lot of real-world examples where negotiation went wrong. Most are not only real-world but really "real" and kind of famous. E.g., there are even some cases about negotiations with terrorists. And it gives a bunch of good practical advice on how to restructure any negotiation so the odds are that both parties will achieve a satisfactory result. And it's not about bargaining hard. You don't have to be a phony. You learn how to be "soft on people and hard on principles."
Expect your attitude towards negotiations to be shaken.