Salary negotiation tips from a former FBI hostage negotiator
A: The first rule of any negotiation is to not take ourselves hostage.
The secret is to have a calm and cool demeanor. Calm is contagious, and that was the strategy of hostage negotiation—to immediately gain the upper hand with a contagious calm, even deferential demeanor. There is great power in deference.
We might feel like the employer has all the leverage—the job we want—and we have nothing because of our need [for the job]. But the dynamic is really based on what is in our own head. In my job as a hostage negotiator, I knew that if a terrorist was communicating with us in any way, he wanted something I could control. That means I have leverage, no matter how it outwardly appears. It's the same dynamic with a salary negotiation.
Source: https://www.monster.com/career-advice/article/salary-negotiation-tips-chris-voss-FBI