I find that really social people who are great at filling every moment with dialogue can struggle greatly with this one.
Sometimes in a negotiation, one party asks for something and - rather than an immediate yes or no - there's somewhat of a pause. Perhaps the person is considering your proposal; perhaps the person is trying to figure out how to let you down gently.
Or, the person is trying to think of a justifiable reason to say no - only to realize they don't have one.
Let them have this moment to ponder that, and come up with a response.
Do you know what tends to happen instead? Guess.
The party that put out the last set of conditions feels awkward and overwhelmed by the silence. And they respond by filling the gap in discussion with concessions to what they themselves just asked for. DON'T DO THAT.
Silence is good. Silence can work in your favor. Do your best to be proactive, and not reactive during a negotiation.
If you're dying to fill in the silence, say something to the effect of "this seems to have been a big ask. I'll let you consider it for awhile." That's it. No need to try to play the other part in the negotiation and decrease your asks to make the situation feel more "comfortable." That's not your job, and it undermines your whole strategy.