I don't do anything fancy - just go over it time and time and time again.
I walk the course repeatedly - both stadium and cc. CC I walk it up to 4-5 times, stadium I do about the same.
I walk the course the first time with the paper in hand, then I walk it without to see if I can remember it without having to look. If I have to look, I walk it again.
Then when I am on my horse in the waiting ring, I will visualize myself riding the course by looking at the fences, and I will even draw the course on my thigh.
If you are determined, you can do it.