A good question is your best means of collecting the information that will help you construct a sale. If you're selling a new surgical glove, for example, you first ask questions to discover the surgeon's concerns so that you are able to point out the specific features of the glove that meet those needs. Without first asking questions, you're reduced to working on assumptions about the needs and interests of your customers. You will do a far better job of selling your products and services if you first use good questions to understand your customer's needs and interests. Good questions help you to see into the mind and heart of your customers, and equip you with the knowledge necessary to make the sale.
Good questions build relationships.
The law of reciprocity indicates that the more interest you show in a customer, the more likely that customer will be interested in you. And you formed that impression because of the questions they asked of you. You can make use of this principle by asking good personal questions of your customers and thereby building strong relationships. Good questions convey the perception of your competence. Here's an illustration.