Hi yashikaaggarwal,
Highly-competitive Schools tend to have AVERAGE GMAT Scores in the low-700s, but the exact Average will vary depending on the specific Programs that you're interested in. It's also worth noting that an AVERAGE Class Score is NOT a "requirement" for Admission - and if you know how to calculate an Average, then you can infer that lots of people get into top MBA Programs with GMAT Scores that are 'below Average' for that Program.
Since it sounds like you're early-on in your studies, then it would be a good idea to take a FULL-LENGTH practice CAT Test; you can take 2 for free at
www.mba.com (and they come with some additional practice materials). If you want to do a little studying first, so that you can familiarize yourself with the basic content and question types, then that's okay - but you shouldn't wait too long to take that initial CAT. That score will give us a good sense of your natural strengths and weaknesses and will help provide a basis for comparison as you continue to study. A FULL CAT takes about 3.5 hours to complete, so make sure that you've set aside enough time to take it in one sitting. Once you have those scores, you should report back here and we can come up with a study plan.
I'd like to know a bit more about your timeline and goals:
1) What is your goal score?
2) When are you planning to take the GMAT?
3) When are you planning to apply to Business School?
GMAT assassins aren't born, they're made,
Rich