I used to really struggle remembering my courses. I would go off course quite a lot! I used to drive my trainers crazy. Now I walk the course twice at least. If it's a bigger class or a Grand Prix I will sometimes walk it three times. After I walk I envision myself riding the course as much as I can before I have to get on. The true test to see if you know it is to close your eyes and tell yourself the course. If I can do that I usually try to not think about it again until I get on otherwise I stress myself out!