I'm assuming you studied by reading the book during class and to whatever degree in preparation for the exam, right? And you failed, right? So your first order of business should be changing your methods to accommodate the situation you're in, or mentally prepare for the same result.
For some people, reading the book over and over again works. For others, you need to be told what to study. This is where adaptive test prep comes into play. A system that evaluates your knowledge and then highlights your deficiencies is key. Just reading page after page of the textbook with no direction isn't likely to get you where you need to be, which is actually understanding the material(not memorizing vignettes of information).
Search the archives. Which test prep resources are good and which are blind money grabs are well documented here. Pick one, and use it. Find out where you're weak, what questions you're getting wrong and then go reasearch why you got them wrong. That's where we transition to understanding the material, not memorizing information.
Mechanically, how you choose to study is a personal choice. Apps are good(some of them), flash cards, writing things out, games and so on. All have validity in the learning process; but if you don't know what you need to learn, beyond saying "this textbook", what you'll end up doing is reading the same information over and over again. Those chosen sections of information will not be what you don't understand usually. You'll re read the sections covering things that sound interesting you you, or things that you like; and you'll feel good about those sections because you know the material and understand what's being said, so you'll come away from a study session with high spirits because you did well in your mind when in fact you didn't learn anything new.
Find out what you don't know and go learn that. The only way to do that is with an adaptive test simulator that tells you specifically what you got wrong; and then taking that information and researching WHY you got it wrong.
You'd think this test was the hardest test ever created with the frequency people post about how hard it is....
