PMP exam was the most difficult exam of my life. I have a Masters degree in Engineering and hold MBA. However, PMP preparation is an intense journey. The most important lessons learn is to take as many simulation exams as possible. I took around 10 exams. The key is that you need to start passing above 80% consistently to make sure you will pass the exam.
Also, it's great if you get a tour of your exam place. My exam was in the morning. Hence, every time I took the simulation exam, I treated that day like my exam day. I woke up around the same time that I knew I will wake up during exam day. I trained myself not to eat or take bathroom breaks for 4 hours. This really helped me.
arash