The biggest advice is to keep diving prior to your class. You’re going to do Deep, Underwater Navigation and Night/Low viz dives along with three other specialty dives that will be determined later. Every dive, whether training or not, needs you to have one thing under control: your buoyancy. So, get some diving done and work on your buoyancy so you’ll be able to deal with the specialty tasks at hand during your AOW dives rather than messing with your trim and buoyancy the whole time. When you have your buoyancy under control, you’ll breeze through the dives. Good luck with it..