What are Trump's top negotiation tips?

"First rule: know what you have. If you have the leverage, use it! Second rule: never let them see you sweat. You have to be strong. Weakness creates aggression in the other side. Third rule: always leave a little something on the table so they think they won too, but make sure you win more. It's an art form, really. Some people have it, some people don't. I have it."