How do you get what you want in a negotiation?

Know your margin. Know how far you are willing to go and write it down in advance. Know what you want. Find out in advance what you want to get out of the negotiation and what you want to achieve. Think about your end goal. There is no point in negotiating without knowing what for. Strive for win-win. Think of an outcome in which all parties derive enough benefit from the agreement.