After you’ve set the appointment, anchor it with commitment using a technique like this one:

“All right Sue, I’m writing your name down in my book for 2:45 on Wednesday. I’ll take myself off the sales floor and make myself available for you exclusively at that time. I’ll also have that Jeep you want to look at cleaned up and pulled over to the side. Sue, I’m scheduled kind of tight on Wednesday, so if you’re running late could you give me a call? Let me get the best number to reach you at on Wednesday in case something comes up on my end, I can contact you as well.” You would obviously change the words to fit your style and product. The point is, to not stop at just setting the appointment. Anchor it with commitment. Build credibility in what your time is worth. Take the time to set a serious appointment and you’ll project a more professional image.