Hi there,
Since you did score higher on a few practice exams, that would indicate that you are capable of a better score than your 530. I generally encourage students in your position not to wait too long to re-take, and to continue to maintain their current skills, while spending some extra time on any specific areas they feel they struggle with. However it's already been a while since that exam. So if you are planning to take the test again in March, you should begin your studies in the next couple of weeks, or definitely in Jan.
As for what to do during your study period, it depends a bit on your skill level and what resources you have access to, and have already done.
It’s important to keep focusing on timing, and practicing on the computer, taking about 1 full length CAT per week towards the end of your studies. Keep in mind that even the real GMAT has a +/- 30 point margin of error, or a given score could vary by 30 points on different days, so that plays a role even aside from your additional studying. If you were not well, I'm sure that played a factor in your previous score.
Assess your current skill level and determine what topics and question types you need to focus on the most. As for Reading Comp, you should use a test prep book to determine a strategy for both the passages and question types, and then practice is crucial, under timed pressure, and on the computer as much as possible. Also, be sure to just READ as much as possible between now and test day, in English. The more you read, the more you improve your speed, comprehension, even grammar (for sentence correction.)
Best of luck!
Jen Kedrowski
Kaplan Test Prep & Admissions
GMAT Teacher
MBA Admissions Consultant
National Product Team Member
