First bit of advise would be to join the ENA and pay less for the exam. Also, the ENA has books specifically designed for the CEN exam (and at a discount for members). The question and answer book is all that I needed to study to pass the exam. I went through the whole book taking about 3-10 questions at a time and looking up the answers, rather than trying a practice test at a time. This method provided something like instant gratification and reinforced the correct answers. I find it hard to do a whole practice test and remember the questions versus the correct answers. When I got to the last practice test, I did do that all the way through in order to build stamina for the actually test. It worked for me since I passed on my first attempt at certification, with less than one year ED experience. Good Luck.