I took a review course which really did not help. The NASN recommends certain books on their website. I think the best guide is in the booklet the test company sends.
I also took the certification test and failed on my 1st try. I have been a nurse for 20 years, but only a school nurse 2.5 years. My problem was I did not study as I should. I felt after being a nurse for 20 years, I did not need much preparation. I was wrong