This is related to your personal teaching style. First, you usually choose the initial class. Secondly, it is best to choose classes with problem situations; 3. Don't choose a class that is too popular. Others don't know how many times they have said it, and it is not easy to speak it well. 4. It is best to choose the class of grade, which is related before and after; 5. Graphics classes should be the first choice, because there are many operations.