Learn how to plan a flight from A to B via C, with D as a diversion. Learn to use the whizz-wheel (edit: use it accurately - some of the potential answers are quite close, so you'll need to be precise). That's all you need to pass, the rest is just the difference between 90% and 100%.
Confuser was identical in style to my Nav exam, but the questions were different (unlike Human Factors, where the Confuser was almost a photocopy of the exam). If you can do the Confuser Nav exam you'll be fine.