The naon materials are absolutely needed. The Core Curriculum helped me the most. Ask questions of every doc you come across. Ask why...most love to tell you what and how they did something.
Ask your clinical specialist for help. If He/she is certified more the better. Study, study, study. Every question you get you will more than likely be able to associate with a situation you came across while working. Good luck, it's a hard, hard test but if you study you will do well.