I took my first practice GMAC exam 5.5 weeks before I was slated to take the real GMAT exam. I didn't do all that well and the math questions especially stumped me. I ended up getting a 27Q and 44V. So I decided to focus all my energy on upping my math score. During the next 5 or so weeks, I aimed at studying 2-5 hours per day, using Glockit practice questions (this is great because you can take them timed and with other people in the chat room), as well as reviewing the 11th ed., 12th ed., and Princeton Review
(Math review) books. I also printed free flash cards off the BeattheGmat website (I recommend it for tips and advice) and also watched Khan's youtube videos about solving various Math questions (he also did a 11th edition review of the quant questions on youtube). In the meantime, I worked through some grammar and reading comprehension questions.
One tip I would recommend following is certainly do more timed practice tests to improve stamina and endurance. On Test Day, I realized I was crashing really badly once I reached the Verbal section; the exam is really structured that way.
Well all that math test-taking strategy practice paid off. I ended up getting a 47Q and wah wah wah a 38V. I scored 4 points below my usual raw verbal score, and I blame that on fatigue. As for the essays, they were a breeze.
Definitely put in the time and effort and your hard work will be well rewarded.
Good luck and bon voyage and remember at the end of the day, the GMAT score is just a small matter; what really matters is your effort once in B-school as well as making connections and honing your networking skills. If people like you, they'll hire you and isn't that the reason we all take the GMAT in the first place anyway? Cheers!