And don't focus on what the other person is losing.
A study conducted by researchers at Leuphana University and Saarland University in Germany explored this in a range of negotiations, including buying and selling used appliances.
In one experiment, participants were divided into buyers and sellers and asked to rate their partner's proposal. In some cases, they received offers (e.g. "The seller offers the refrigerator for a price of €160," or, "The buyer offers a price of €160 for the refrigerator"). In other cases, they received requests (e.g. "The seller requests a price of €160 for the refrigerator," or, "The buyer requests the refrigerator for a price of €160").
Results showed that both buyers and sellers were more likely to concede when the other person focused on what they were going to gain from the negotiation (offers), in contrast to what they were going to lose (requests).