In grad school I was a TA (Teaching Assistant) for more years than I care to count. And last year, I taught three undergraduate classes of my own. Over the years, I have learned a few things about teaching (for what it's worth, the subject is history):
1. The "absent minded professor" routine doesn't work unless you are truly absent minded.
2. It is usually--almost always--inappropriate to introduce your own political views in the classroom. As teacher, you have a "bully pulpit" that none of the other students--even the bravest and most vocal--can enjoy. Even if students are not intimidated by the fact that you have the power to determine their grades, you still have the power to open and shut off debate. Use it wisely and only for subject-related, course-related goals.
3. When teaching a controversial issue or any issue that admits of more than one interpretation, present as many legitimate sides of the issue as possible.
4. Just because you were an excellent student does not, by itself, mean you will be a good teacher.
5. Good teaching to a large extent is an art, and that makes being a good teacher very hard. However, certain of the "professional" requirements of being a good teacher are very easy and should be lived up to, even if you are otherwise not a good teacher. These include showing up to class on time, honoring your office hours, meeting with students when you say you will, responding to emails within a reasonable length of time, and grading papers promptly.
These are just a few. I'll add more if and when I think of any.