Visualize the jump. Visualize it from your perspective (What you hear, feel, see, smell even taste everything is important) then visualize like a camera was taping you and your watching the replay. After you visualize youreself landing it 3 or 4 times tell yourself I can land this trick until you feel confident (I do this befoire every time I try a new trick or even a hard trick that I can already do). The reason I started to do this was because I broke my arms (yes arms as in both) snowboarding and was scared as hell to break something else. So after everytime I did this I would feel confident and believe I could land it so I wasn't scared to break something. It has really helped my riding and I've improved so much just by doing this and getting over my fear. Hope this helps you with your problem.