I used the KMK books and course, and some of my class notes. I started studying 3 months before the test, and read through most of the material twice. Obviously you want to spend more time on big topics like Anatomy, Ocular disease etc. I'm not a good test taker overall but I did fairly well on boards by simply putting in the time. One of the things I liked about studying for boards part 1 was that I felt like I was going over material I really wanted to internalize and know like the back of my hand. I actually enjoyed those 3 months and it was probably the most beneficial study I ever did in Optometry school.
Hated the test though... I felt like it was designed to produce a bell curve instead of actually testing the things an Optometrist should know.