As I approach 20 years of teaching, here are some things that have worked well for me.
Revise lectures the day after. After giving a lecture, I used to jot down some notes on how to improve it, and then the next time I taught the course I would have no idea what the notes meant. Now, however, I revise each lecture a day or two after I give it. It’s still fresh in my mind, and it makes it fresh for the next time. (Got this from a colleague).
Finding great videos. This works so well. I give an extra-credit assignment for students to find videos, on YouTube, that illustrate a concept covered in class and to explain why. After they turn in the assignment, I go look at the videos and take the ones that would fit well with class. This produces funny, relevant videos for the next time that I teach the class.
Using videos. Videos on YouTube sometimes disappear. So, I now use clipgrab to download the video onto my portable hard drive (which what I do all my work on). Then, I embed the video into PowerPoint slides for lecture, thus always having it in the future. (Note: resolution of 480 is fine. Otherwise file gets too big.)
Make it a mystery. The most common problem I see in my own and others’ teaching is what I call “flash-card teaching.” Here one idea is presented after another, like going through flashcards, without an overall narrative. There are various narrative forms that work, but the best is telling a story as a mystery. Robert Cialdini explains how.