When we launch a new campaign series, it includes 4-5 new drawings. I will work out the composition/hidden drawing and then take a digital photo of it and print out on photo paper. These print-outs are my "guides" and go in a 3 ring binder.
Then I will practice each one of these drawings 3-5 times along with my music soundtrack just to make sure it will work out timing-wise. It is during these practice times that I tweak the composition and colors, trim or add details, etc. I may take a new photo if a lot of changes have been made from the original.
Just before a program, I will be backstage (we haul and set up stage curtains) going over the photo of the drawing for that night. I'll study it for a couple of minutes just to remind me of colors, proportions, details, etc.
That's pretty much how I do it. I'll post a photo of the "practice booth" I recently put up to contain the dust.
Hope that helps!