First, in order to avoid wasting time, I like to quickly evaluate the student's level but also interest and motivations.
Then, my speed will be adjusted to the student's capabilities.

I don't like to "go back" to some material, unless really necessary, of course, and so I try for a subject to be clear, with explanations, real-world applications, worked examples, problems, etc, before we move on.
Above all, it needs to be interesting, as well as useful.