Hi Taresh,
Raising a 500 to a high-600s or 700s score will likely take at least another 3 months of consistent, guided study - and you'll have to make significant improvements to how you handle BOTH the Quant and Verbal sections. As such, you might want to consider pushing back your Test Date.
Before I can offer you the specific advice that you’re looking for, it would help if you could provide a bit more information on how you've been studying and your goals:
Studies:
1) How long have you studied?
2) What study materials have you used so far?
3) How have you scored on each of your CATs (including the Quant and Verbal Scaled Scores for each)?
Goals:
4) When are you planning to apply to Business School?
5) What Schools are you planning to apply to?
GMAT assassins aren't born, they're made,
Rich