Before the semester begins:

Prepare a detailed course outline, with each lecture or class session described in one or two lines of text. This forces you to organize the course.

Prepare an information sheet that states your policies for grading, late work, and cheating, your office hours, exam schedules, and course materials.

New lecture notes:

Organize each lecture carefully. What are the one or two key concepts for that day's lecture? What concepts or techniques will the students find difficult? What examples can you use to illustrate these?

Write out your notes. Include what you plan to write on the board. Build in time for questions—students to you and you to the students. Plan some questions.

Rehearse your lecture out loud at least once.

Old lecture notes:

What can be improved?

What new examples can be used?

Rehearse your lecture.

Half hour before the lecture:

Pull the phone plug, and put up the Do Not Disturb sign. Read through your lecture with care.

Relax.

In class:

With self-confidence, because you're organized and prepared, present the material.

Invite comments and questions as you go along.

Seek to understand whether students understand.

After the lecture:

What went wrong? What was not understood? What could be done better?

Jot down comments on your notes.

Other things:

Be accessible, always meet office hours, allow students to interrupt you in your office when convenient.

Treat students with respect, as colleagues. They pay you to do what you love to do.