Contrary to what everyone has been saying in the posts, I blame my singular focus on OG for my downfall last time. OG is invaluable, but only after one has developed some solid strategies. I felt I had no strategies going into my GMAT attempt last time.
To correct for the lack of strategy, I spent both time and money on the following material...
1) I bought all Kaplan
literature available out there; the math workbook, the plain 2004 book and of course the 800 book. I feel I truly benefited from these books to form a strategy for quant. I think 'picking numbers' and 'backsolving' - regardless of how obvious they sound - are some of the best strategies one can pick from these books.
2) I spent $27 on the deltacourse material. I had a complex about perm/comb and probability and really wanted to clarify my concepts. The deltacourse truly helped on that front. The sample questions that they have helped me boost my confidence. I felt really comfortable on the perm/comb front going into GMAT this time.
3) I had heard that Princeton review was good for verbal. So I bought it, and strongly recommend it for preparation on the verbal front. Although my verbal score of 38 does not qualify me for giving out useful advice, I highly recommend Princeton for verbal prep.
4) I plunked money on buying all the ETS tests. These are a bit easier than the real deal, I think, but an excellent excellent way to get true ETS-style practice.
5) I gave practically all Kaplan
and Princeton tests that come on their CDs.
6) Finally, once I had gone through all the above material, addressed my weakpoints and prepared a mental strategy, then I launched a full-scale assault on OG. I solved at least 100-150 questions in each category backwards, noted down questions I could not solve and then attacked those again.
I studied practically every day for the past 2 months and spent at least 4 hours per day on studying. I just practiced, practiced, practiced and practiced. As you said, the key is to not panick during the exam and I worked really hard on that by putting lots of efforts in preparation and giving a lot of of computer/paper tests in the 2 weeks before exam.
There is so little difference between a score of 540 and 700+ that it is really just a matter of not losing your nerves during the game.