There are several things it takes to make a good class:

A clear organization of the course, web-page with
schedule, assignments, lecture notes, practice exam,
grading scheme, so that you know what is expected of you.

A good choice of text and syllabus, taking into account what 
you know from before and what is important for you to learn.

More specific things about how to explain various things.
This comes with experience. Reading different books to get
different perspectives. Thinking about it and experimenting 
by trying to explain things in different ways.  

Stimulate your curiosity and interest by showing how useful
the material is and raising challenging questions.

Perhaps the most important part of the teaching is the 
interaction between the teacher and the students.  

You can help making this a great course by looking at the 
material before the lectures and asking questions in class.
This will help you and everyone else follow the lectures.

It is somewhat challenging making it interactive and personal with 
lots of people in a large room so your participation is needed.