There are quite a few ways to convince the interlocutor. Their number reaches several hundreds or thousands. However, they are all based on the six basic principles that Robert Chaldini described.
Law of Deficiency
Highlight the uniqueness of your proposal. Indicate that it is not always available. Hint to the client that he may be late, saying "No" now.
Example. Coupon sites actively use this method. You can see how many goods, services and days are left before the end of the action. People carry out an order even if there is no de facto discount.
Power of Authority
People are more likely to trust those they consider experts. To convince a partner, find out who he considers authority, and who does not.
Example. The German Chess Federation wanted the Ministry of Finance to recognize chess as "a useful sport with educational value." Then the Federation would receive benefits. The decisive argument was a quote from the letter of King Frederick the Great. He wrote: "Chess fosters an inclination to independent thinking." The federation chose not to quote the end of this phrase. He added: "... and therefore should not be encouraged."
People are more likely to say "Yes" to someone who has done them a favor. Think about what good you can do to the client before starting a conversation.
Example. In some restaurants the waiter brings a chewing gum with the bill. It's not that expensive, but it's pleasant to come back here.
Principle of Consistency
People love to look consistent. They cherish this image. Remember often what the partner promised you and hint that he is a man of his word.
Example. Let's say you do not have enough money. Before you take a large amount of money from a friend, take small ones and regularly return them. So the person will get used to the idea that you can be trusted something more.
It is very difficult to come to an agreement with the one who causes antipathy. Try to adjust to the values of the interlocutor. People tend to support those who are like themselves.
Example. Experienced businessmen try to learn more about the opponents before the talks: what they like, what they do, what kind of hobby they practice and with whom they are friends.
The majority focuses on their social circle. Scan the closest client environment. Find out who he considers authority. Work with opinion leaders. Collect positive feedback about your company.
Example. This argument is often used in online stores. You can see labels on product pages, such as "Buyers choice", "Most popular" or "Often bought with this item".
Social skills are of great importance in business. They are necessary at contacts with clients, negotiations with partners, hiring of employees. It is impossible to master all the techniques. However, it is realistic to apply the basic principles of communication.