Keep it simple.
I wrote a lesson where I went into way too much detail. I tried talking about the Boston Massacre and the Boston Tea party, two events that I felt (probably as an old history major) were important to the American Revolution.
However, I think that this was way beyond the students grasp, or the zone of proximal development. The students had a difficult time knowing what to do, and I think I pushed the limits on what I should teach.
I need to remember to not do this... to just keep things simple.
Even though it means completely changing a lesson for tomorrow, I'd rather teach them simple, basic stuff, than the really complicated items.