I started off backwards...read the PMBOK Guide cover-to-cover (thought about quitting). Bought Rita Mulcahy's PMP Exam prep book. Read it cover-to-cover and did all the exercises. If I missed a practice question, I went back and figured out why I missed it (really, really thought about quitting at this point). Watched the PMP Prepcast...quality was excellent, though it felt like someone was reading me the PMBOK Guide so it was hard to stay engaged. I did memorize the formulas, but on my test I only needed them for a handful of questions. I did no other practice exams. Spent about 2-3 hrs. a day on this M-F for 5 months. I was certain I was going to fail first try, glad I didn't quit.
Good luck to those of you studying for your exam - don't quit!