Hi Ammu,
"Mixture" questions are a relatively rare subject on the Official GMAT (you will likely see just 1 question that fits the typical 'pattern' of a mixture question), so if you're looking to pick up big points on the GMAT (specifically in the Quant section, then you're not focusing on the right subject(s). Since you're still studying, I have to assume that you're not yet hit your score goal. Before I can offer the most specific advice that would help you to get to that goal, it would help if you could provide a bit more information on how you've been studying and your overall goals:
Studies:
1) How long have you studied?
2) What materials have you used?
3) How have you scored on each of your CATs (including the Quant and Verbal Scaled Scores)?
Goals:
4) What is your goal score?
5) When are you planning to take the GMAT?
6) When are you planning to apply to Business School?
7) What Schools are you planning to apply to?
GMAT assassins aren't born, they're made,
Rich