The Professional
As a top notch twenty-five year professional, I believe communication and the way you are dressed makes and important statement about you.
I address my students with a surname [to show respect] and I encourage and open learning environment for them to learn. My appearance shows my sincere intentions in acheiving excellence from them and me. My lectures and hands on work re-inforces this committment on my part.
Yes, I also use surnames: Mr. Smith, Miss Jones, or Mrs. Jones (as the student prefers). I find that this practice maintains a respectful, businesslike attitude between student and instructor. (Being a simple 20th Century guy, I eschew the trendy Ms Jones.)