Even after 6 years of regular teaching, I still like to plan out my classes. It helps me to see which muscles I need to strengthen, which to stretch and that I have covered all the main points.
When I first come up with a new class theme, I just do a brain dump of everything I can think of to do with that theme, whether its warmups, peak poses or pranayama.
I then further refine things by grouping things together, like by difficulty level so I can create a series of classes that progress, or by pairing up warmups and activating exercises with peak poses. This means I can create multiple classes from one braindumping session.
I will then try it out a few times to make sure things flow nicely and I do keep a pen with me during class in case something doesn’t quite work, I can annotate my class plan and keep repeating or coming up with new variations.