Ask them questions and listen to their answers. If you are selling something, tell the person how it will benefit them to own it. You are helping them solve a problem. When you are convinced that what you are offering can improve the person's life, your fear of calling subsides. You might still be nervous, but remember that the person will be better off for taking your call.
People look for guidance from others who are more knowledgeable.
Supply that knowledge with the absolute confidence that it will benefit your caller and you will find people will respond to you in positive ways. Try to follow that call with one you know will be positive. Realize that some people have poor personal relations skills or emotional control. Get right to the point. When speaking to a Louisianian with a lazy Southern drawl, slow down.