GMAT Strategy

Hey, guys!
I have 11 days left to GMAT re-exam and started to prepare a couple of days ago.
I took my first GMAT exactly 2 months ago - 610(Q35, V39), no preparation at all. As i am currently writing a thesis and having a bunch of additional courses, it was not possible for me to start preparing for the re-exam before.
Im relatively good at verbal section, with virtually no mistakes in CR and SC questions. But math has been a curse for me. Well, i know the material and am able to solve 80-90% of the questions correctly...but i am a slow thinker, thats always been my problem. I try to practice as much as is possible from OG, Kaplan 800, and GMATprep/Kaplan tests.
About me: a bachelor student in economics, need to pass GMAT for master application, 700+ preferred score
Please, be kind to share the strategies for boosting math score! I am really looking forward to the answers!

I'm now studying with the KAPLAN Math workbook and I enjoy the knowledge it gives me. I don't want to say that I'm weak in Math, but as I had decided to be totally ready , I bought it.
There are a lot of different "to solve fast" strategies in it, which can help in your situation.

But I don't think it will improve your math completely.
The most frequent suggestion on this forum about your case is taking online CAT tests to build strong time management.

Anyway. I think gurus will tell you more below
I'm the beginner.