I found I became much more confident speaking in front of a group of people by TAing CS classes in college. (The responsibility was typically to do about an hour a week before class as well as help with assignments.) Not only do you learn material really well when you have 30 people's worth of questions about it, I also had a good time of it. Some of my favorite student feedback:
- in response to me telling my section that I do not require attendance and that I would fight requests to do any pop-quiz like behavior:
"I love you."
- at the end of the semester, anonymous feedback:
"He didn't shave a lot of the time."
I feel like I got lucky with the TAing thing; I wish it had been emphasized more in school. Knowing what I know now I definitely would've traded off taking one fewer class for teaching once.