I just finished my first real GMAT-test with a score of 730 (Q49, V40).
Since I have found the experiences of others posted in this forum to be extremely helpful I will share with you my own experience.
A quick academic background check. I am 25 years old, from Denmark (non-native American speaker) with a BsC in Economics and I will be getting a MsC in Economics by early 2010.
I started my preparation a little more than 2 months ago. On the advice of a friend of mine (top 15 MBA-school grad) I started out preparing for maths using the CAT's of 800score.com. Seeing my first results felt equivalent to being punched in the mouth by Albert Haynesworth (at least that's how I imagine that would feel): I scored much lower than expected, generally around 35 (44th percentile). Thus I realized that I had a lot of work ahead of me.
I began studying the quantitative guide at 800score.com. This is actually quite a good guide which covers most of the topics that are asked in the quantitative segment of the GMAT-test. However, it did not feel that I significantly improved my score.
Next up was the Kaplan CAT's. This was the first time I encountered the verbal section of the GMAT and I could finally get a total score. This, however, was not a:

kind of moment. I scored in the 550-range in the two tests that I did from Kaplan. So I was kinda desperate. I needed to get above 700 and it seemed I had a long way to go.
So I started "googlin" and found GMAT-club. And boy, that was a difference maker. The first thing I noticed was the review of the CATS (
https://gmatclub.com/forum/all-gmat-cat-practice-tests-links-prices-reviews-77460.html). Those I had come across until that point were rated quite low on this list. Reading around the forums quickly made me realize that I really needed to get the Official Guide. So I ordered that. While I waited for the order to arrive, I started browsing the quantitative forums here. What a resource! The taglines allowed me to find the questions where exercise was most needed (a special thanks to Bunuel for providing very challenging questions and good explanations when needed).
Another great feature is the GMAT-score estimator. From this tool I learned that a 550 Kaplan score was equivalent to a 630 GMAT-score.
Furthermore I tried the free tests of GMAT-club which were challenging - but I managed to do quite well, scoring in the 60th-70th percentiles (considering there are probably many re-takers I was satisfied with these results).
When the OG finally arrived there was just 7 days until test-day so I decided to take the whole week off and just read this book. I did the Diagnostics test with the results:
PS - above average
DS - excellent
RC - excellent
CR - excellent
SC - above average
So I decided to give 100% focus to PS and SC. During the week, I did 180 of the PS questions and 50 of the SC questions and wrote an
error log. On day 3 of the final week I did GMAT-prep #1 for the first time ever - and scored 740.
740? 740? WTF??? This was much higher than I expected. So naturally my confidence level rose. But it could have been just a fluke, though. However, on day 5 I did the GMAT-prep #2 and this time I got a 760! Obviously I was pretty much down with this GMAT stuff by now.
On the day before the GMAT I briefly reviewed my
error log and that was the only GMAT-related activity on that day: My brain got a well-deserved rest.
Then came test-day (today). I had a perfect nights sleep and came into the test centre 30 minutes before test-time with only a slight anxiety disorder. Armed with two cans of energy drink I took on the test. A was not really nervous during AWA's since I had read on this forum that they are rather insignificant. While some find them exhausting, I actually liked them since they allowed me to reconcile with the atmosphere of the testing room and served to relax my overloaded nervous system.
The math part was fine. It accurately resembled the GMAT Prep software experience. However, I do think that the verbal part was a bit harder in the real GMAT than in the GMAT Prep software. Particularly, the RC questions seemed to be tougher and I'm pretty sure that they were the reason that I scored a bit lower than in GMATPrep (I had no errors in RC in either GMAT Prep test).
Then came the score: 730! Wuhuuuuuuuuuuuu! TTYN GMAT!
In conclusion I would like to thank BB for running such a great site. Although impossible to quantify, I will claim that this forum added at least 30 points to my score. Being able to gauge the difficulties and experiences of other "ordinary" test-takers has be invaluable.
[And just before I'm out, check out this thread for test-day advise
https://gmatclub.com/forum/gmatclubbing-administered-770-50q-45v-86239.html. I followed most of his test-day advise, however I did not take the meds recommended. And perhaps more importantly, I didn't drink Gatorade. That might serve as an alternative explanation as to why my test result came 10-30 points short of my GMATPrep results ;-D ]