I started with the Jepp Instrument Question/Answer book. I'd go through that a chapter a night, highlighting questions I either missed, or guessed at. When I finished going through the questions, it was easy for me to go back through and study my "trouble areas."
I also used Sportys.com. They have it set up where you can take a practice test or study a specific area. Here's the
link.
Finally, Chewie, hooked me up with his King's test prep CD. (Another way Jetcareers has helped me out. I'll remember to pay it forward.) I used that at least once a night to generate a practice test. The program also keeps track of your missed questions and shows a graph of what your weak and/or strong areas are. This really helped me to study my problem areas.
So, when all was said and done, I knew the material, but I also felt like I was taking the test out of memorization.