As an undergrad at MIT I tutored for both freshman physics and introductory computer science classes. As a graduate student at MIT, I was a recitation instructor for freshman physics and a teaching assistant for honors freshman physics and several astronomy/planetary science classes. I also developed a 2 week C programming class which I taught 6 times.
I believe it is very important to *understand* a problem and its solution, rather than just getting an answer. When tackling a difficult concept, it helps to break it down and understand the parts, and then put the pieces together.