From Never Split the Difference by Chris Voss.

Active Listening

Negotiations should start by focusing solely on what your counterpart has to say. Doing this not only calms their unconscious mind, but your own. Allow them to talk, and truly take in their words. It will help later when you try to influence their behavior. Your goal is to identify your counterparts needs, and to strengthen their feeling of safety.

Mirror their words. Take the last one to three words of what someone has said (or just the most important) and repeat them back in the form of a question. Repeat them back? Yes, it prompts them to keep talking, without steering what they say in any direction. When you ask a question, you force them down a particular path, which might not be where they wanted to head.

Tactical Empathy

Label barriers. When you realize your counterpart has an emotional barrier to negotiation, point it out. Never use the accusatory you, and never use the self-incriminating I. Simply say "it seems like," "it sounds like," or "it looks like." Then go silent. The idea is to label fears that your counterpart has, or accusations that they may have for yourself, in order to clear that barrier for future negotiation. Labeling these barriers disarms them.

Allow for No. People have two needs, the need to feel safe, and the need to feel in control. You must satisfy both, and you can achieve both by allowing your counterpart the opportunity to say "no." No starts the negotiation. It should not be avoided.

Summarize. Eventually, you should rearticulate what your counterpart has said, in your own words, and then label their emotions behind the statement. The magic response is "that's right." When they confirm that you are right in their world, you can make progress.