I honestly don't know how I could have been more prepared for this exam. I took the PPI course, I took the practice tests, I put the hours in studying. I was militant in my discipline to study - it drove my wife crazy.
In some ways it seems like it comes down to luck. As in you know your stuff and you just gotta get lucky on 3 or 4 multiple choice questions on that day to push you over the edge. I hate saying that because it goes against my "you make your own luck" philosophy, but when it's a multiple choice test there is some luck involved.