Just get in your minds eye a time when you have competed really well and everything has gone perfectly, imagine yourself riding that course or scary jump and how well it has gone for you! Keep going over it, put the scary bits behind a trapdoor in your head and everytime they surface close them back in! Good luck, you wiil be fine!
Just remind yourself that your horse doesn't know it's intermediate, he'll just think it's a big novice track. Oh, and a glug of Rescue Remedy always helps me.