First of all, let's do a questionnaire survey to see what students don't understand the most and what questions are most likely to be wrong. Isn't there an exam recently? What questions may need to wait?
Secondly, it is suggested not to talk nonsense. For completely meaningless topics, such as solid geometry, vector method is simply a template for solving problems. This is basically known to all. Even if this method is generally used in exams, it will be very boring. But if geometry is proved by ordinary laws and theorems, it will be interesting and worth a try. By analogy, if the teacher talks about some knowledge, you will be distracted, so don't talk about it. Find something interesting, use your head a little, everyone can master it, and people will get excited. You must use your head.
Finally, determine your own lecture style, choose what to talk about, don't entangle, and do it well. Classes can be fun, but it's best to give people a sense of trust. Don't let people think it's just ... the audience may know each other.