I like to focus on how the subject relates to a student's own life and experiences. Physics is "the study of nature" and so it can be seen all around us at all times. I sometimes use video clips or other online resources to help the concepts come to life. What techniques would you use to be sure that a student understands the material? Usually I will have a student explain a concept back to me. If the student is working on problem solving, I provide multiple sample problems of increasing difficulty to make sure that the student understands thoroughly.