Hi aman2139,
Many GMATers (both native and non-native) find SCs to be challenging, so you are not alone. Thankfully, the SC rules that you will be tested on in the Verbal section come from an established (and limited) set of Grammar rules. In that way, it's fairly similar to Geometry (re: if you don't know the rules, then it's difficult to answer the questions - but once you DO know the rules, then most of the work is just about using the proper rules for each prompt).
Before I can offer you any additional advice for your studies, 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? How many hours do you typically study each week?
2) What study materials have you used so far? What “brands” of CATs/mocks have you used?
3) On what dates (or approximate dates) did you take EACH of your CATs/mocks and how did you score on EACH (including the Quant and Verbal Scaled Scores for EACH)?
Goals:
4) What is your overall goal score?
5) When are you planning to apply to Business School and what Schools are you planning to apply to?
GMAT assassins aren't born, they're made,
Rich