1. Have a few clients tell you/write what it's like to train with you. Have them describe the changes they went through, the emotions connected with training. It will help you get an insight into what you deliver. As trainers we think we "drill a hole in the wall" (to quote Alwyn) and this is what people want (results) however it is how they "feel" that makes their friends want to work with you. You will see that you give more and different things to people than you thought. Then, you can explain what you give during the consultation process.
2. Have a book with results and testimonials that you can let them flip through when you explain who you are and what you do
Your approach will differ from person to person, but the basics are the same. They need something from you - a goal, a promise, hope, program, diet, whatever. Find what they need in how they speak to you. Then again, if you don't find compatibility that's fine, too.