Make objections work for you
Objections should be sought out and resolved throughout any sales presentation. This allows the salesperson to judge how the sale is going, and to assess the buying motivation of the customer as each feature of the product or service is explained.
Source: Bill Fitzpatrick, sales trainer
Some sales trainers describe this process as "taking the customer's temperature," or "trial closing," and each of these terms describes the process fairly well. I like to call it "teaching the customer to say YES!"
I feel if I can get the customer into the habit of answering yes to a series of questions throughout the presentation, when the final question to buy comes, the result will be very predictable.