I would start out small and do dive rolls and gradually get higher.
You could also visualize yourself doing it and think positive. I can't really help much because I have no experience with such hard passes. Hope I helped.
Prep Op is like compulsory but instead of just working one level you work different levels on different events. For instance, prep op silver is level 4 and 5 combined (which is my level) i do a level 5 bars routine, level 5 floor, level 4 vault and level 4 beam.). There are also less practices...