I would strongly recommend going through a test-prep course. I took kaplan when I was in high school. The benefit of these classes is that you have other students there to motivate you and usually homework assigned. With just a book and self-studying, it's easy to put it off and not really find the exact answers to your questions. With a class, you have an instructor to help you with any and every questions, as well as other students, and a deadline/schedule to follow so you have to do the work. They offer several practice exams so you can track your progress and some offer score guarantees. I did very well on my SAT's and recently took another class to prepare for my GMAT exam for grad school. It's a worthwhile investment if you're serious about the exam and getting into a great school.