As human beings, we're powerfully swayed by how much we feel we're being respected. People comply with agreements if they feel they've been treated fairly and lash out if they don't.
Negotiation is often described as the art of letting the other side have your way. You have to give the other side a chance to put stuff on the table voluntarily.
Salary negotiations are particularly important because people are testing you as both a co-worker and an ambassador. They really don't want you to be a pushover, and they don't want you to be a jerk.
As a negotiator, you should strive for a reputation of being fair. Your reputation precedes you. Let it precede you in a way that paves success.
'Fair' is, like, this incredibly overused term in negotiations: 'I just want what's fair.' 'What's the fair market price?'
In reality, every single negotiation involves another commodity that's far more important to us, which is time - minutes, hours, our investment in time. So even if you're talking about dollars, the commodity of time is always there because there has to be a discussion about how the commodity of dollars is moved.