Getting to Yes is a popular treatise on how to negotiate effectively. Research on bargaining tactics was conducted by Bruce Patton of the Harvard Negotiation Project, and distilled into book form by Roger Fisher and William Ury.
In the very first chapter of the book, it provides:
Arguing over positions produces unwise outcomes. When negotiators bargain over positions, they tend to lock themselves into those positions. The more you clarify your position and defend it against attack, the more committed you become to it. The more you try to convince the other side of the impossibility of changing your opening position, the more difficult it becomes to do so.