If possible, a guest speaker works well in a class. Pick one who is dynamic and has a passion for their vocation or it can go bad quickly. Years ago, I had a guest speaker in a class who did nothing except brag how well he was doing in his shops. I thought the topic was laid out in advance, yet at the last minute he changed course, came in late, and created a disaster for the students. Since then, we've used other guest speakers via conference call and it has worked very well.

When beginning to teach, it is vitaly important to develop an image as the instructor. At first, I believe, it can be as simple as respectful. Fairness may take several classes to define. Also, I believe the image should be tweaked occasionally, nothing major, just small minor adjustments because class dynamics change by virtue of us aging and the students getting younger! The core image, respect, fairness, etc. should not change.