I did the 60 day prep program and used the videos with some amendments since I got married in the middle of it. First test I took with no prep, I scored a 690. 2 weeks later, I scored a 710 (was elated). I spent the next 4 weeks absolutely killing myself studying. I was studying from about 8:30 until 3 AM just about every night. The week of the test, I got a little confused. I didn't know what to do because I had completed 3 practice tests, every math problem twice, and every verbal once from OG. I SHOULD have just relaxed, cleared my head, and trusted myself.

That's what I should have done.

Instead, I stayed up even later. I even pulled an all nighter one day that week. I took the day off of work the day before the test to really kill myself preparing.

I bet you can guess what happened test day. I woke up feeling ill. My eyes hurt. My head hurt. My brain was a mess. I scored a... 590. I wanted to kill myself.

I knew I was better than that, but my confidence and resolve was at a very low level. My wife finally talked me into giving it another crack 2 weeks later. When I checked the GMAT site, though, there were no available test dates. Then I saw that the GRE is accepted at tons of schools.

I signed up for the GRE, and had 4 weeks to prepare. I took a completely different plan. I would prepare, but would not kill myself. I took 2 practice tests just to get the feel for the test. I did maybe 4 hours of math prep over the next month (GMAT math is way harder). I did verbal prep for maybe 10 hours total over the next month. Test day rolled around, and I was in a completely different state. I was relaxed. I felt confident. I wasn't frazzled. I scored an equivalent of a 700.

So, take the advice listed above. Study for the test. Study very diligently, but do NOT kill yourself.