My preparation for a 700 GMAT score is going pretty much as planned: spending a significant part of my free time doing questions (and more questions) and refreshing concepts of basic math and English.
I´ve almost finished all the questions in the Oficial Guide and my success rate is quite high in both Verbal and Quant sections, although I guess I need to take it even higher in the latter one If I want a 700 score, since the 80th percentile in the Quant part is at 48 points . I will also need to pace myself better, because there are sets of questions in which I need more than 2 minutes per question; of course I don´t skip any question, which means taking 5 min to get it right if necessary, for I am still in that first phase in which I rather do it right, or try to think the better way to approach each question, than do it fast.
Another important factor will be to avoid silly mistakes. It really bothers me when I give a wrong answer to a question only because I did not read it right or completely (or because I added a quantity at one side of the equation and substracted it at the other side…). Of course it is a matter of paying more attention and practicing, but a mistake is a mistake in the end, and many of those I´ve made when facing Problem Solving questions have come as a result of a lack of focus, and it is really anoying when you do everything right and fail because you did not pay attention.
And GMAT is mostly about paying attention. Paying attention to details. Really hard questions often involve the easiest mathematical concepts (or grammatical), they just have put it in a way that it is difficult to realize what you are being asked or what it means/implies the information you have been given. It´s like camouflaging the questions. But that´s what it is being tested, your skill to take into acount those small details that turn a 5 minute question into a 1:30 one. Your analytical skills.
The good news is that, as everything in life, you get much better with practice and time.