They all follow a procedure that includes asking questions and listening to the customer. This article doesn't allow space for me to go into any great detail, so let me simply say this. Any well designed sales procedure will have eight steps that start with building rapport and end with closing the sale. If not, you should look at other courses. Offer people options.
People love to buy but they hate to be sold.
Movie theaters, grocery store and clothing stores all understand the principle of options. Great sales people do too. By offering options you allow your customer to remain in control and you allow him or her to compare your one service to another one of your services rather than compare it to what your competitors offer. Offer your customer options. They'll love you for it, your sales will go up and so will your profits.