1. "Nibbles": Reach a general agreement (agree on a basic premise). Instead of instantly accepting the deal, push for one small concession at a time.
2. Before entering into a discussion, think about a 'BATNA' = Best Alternative To Negotiated Agreement. Are there other options? Is there a minimum you are willing to agree with?
3. "Expanding the pie": While certain points in contention may be very inflexible (salary, job position), "expand the pie" and seek out other areas which may be more flexible (vacation days, compensation). This also serves to clarify the central hinge of the negotiations.
4. Disarming Empathy. Essentially, the act of being empathetic (in a sort of self-deprecating way perhaps?) so that the other side bargains against themselves while you do not budge from your initial offer.