I studied for about 12 weeks.. anywhere from 15-20 hours a week. I took the diagnostic exam first and didn't do too well. Spent 3 weeks going over the Princeton Review book, and then took one of the practice exams PR provided. Went from a 490 to 590 but still nowhere near where I needed my score to be. The next 7 or 8 weeks were spent going over OG11.. and the last two weeks I just reviewed a lot of the questions and practiced with GMATPrep exams. I took each GMAT Prep exam twice and scored 680, 610, 670 and 740. I think the last one was an aberration because by that time I was seeing a lot of repeats (but still good practice nonetheless, and possibly confidence booster?).
I think you should be OK if you're scoring around your target with the GMATPrep exams.. everyone might be different but I tend to focus more when it's the real deal and I figured a 20-30 points increase is possible (of course, a decrease is too, but luckily that didn't happen).
My suggestion for studying would be to get two books, one from Kaplan or Princeton Review or something and the second The Official GMAT book. Go through the first book and learn the theory behind how to answer the questions and do their practices. Once you've done that, go through The Official GMAT book and do the real problems. Of course, utilize the resources on this site!
A few random thoughts:
-I can't emphasize enough how important GMATPrep is.. it's exactly like the real exam so practicing with that will prevent any "surprises".
-If you get stuck on a problem, just drop it, guess and move on. This was my problem during practice and it cost me valuable time. During the real exam, I figured it might be a experimental problem, so just guessed and went on to the next one.
-Try to keep your focus on the second half of the verbal.. by that point I was tired and I noticed I wasn't as focused as before (especially on RC), which might have cost me some questions at the end..
-Take the breaks, take a walk, regain your composure, clear your mind, grab a drink, eat a snack, whatever.
This was one of the worst exams I've taken. I really did not enjoy one bit of it compared to other exams. You don't learn anything "new" content wise, and you're basically learning how to take an exam. It's like a game, but one that's beatable. So, good luck!
