Started studying in July...took about a month off twice, once in September and once in December. Used all of the math guides, and to a lesser extent the verbal guides. The goal was to score 700, figuring that would be a great score since I've been out of school for over 20 years.
Was scoring low 600's on the practice tests until I came to forum for advice on timing issues on the quant ( was leaving 8 or so questions unanswered). I received some great advice from Stacy, then took about 3-4 days practicing timing on difficult quant problems. Took another practice test, and scored 690. It was a great confidence builder. I took the GMAT today (a week later), and scored the 710. Very happy and thankful for the timing issue advice which turned everything around for me.
My unsolicited advice:
1. Have realistic expectations.
2. Take time to learn fundamentals, and learn them early.
3. Don't neglect strategy. It might just be the thing that makes the difference in getting to your goal score. It did for me. But first things first - fundamentals, then strategy.
4. Use the Manhattan GMAT practice tests to practice timing and pinpoint areas that need improvement, but later also to recognize areas where there is little hope for improvement - so that you don't waste time on problems that you'll probably get wrong anyway.
5. Learn to recognize traps and make educated guesses quickly.
6. Relax and throttle down the last week or two before the test.
7. Don't fret. It really is just a test.
Good luck everyone!