Hi Swati,
Its nice to see a fellow Indian starting out on the GMAT journey. I just started my prep this month.
I would suggest your first step be to give a GMATPrep practice test. That will determine your present standing. Use it to determine your strengths/weaknesses and the current score. It will also help you set a realistic goal and how long you might need to get their.
Once you get where u stand, the next step is to determine how you want to work on your weaknesses. Get the 8 Manhattan guides, if you plan to study on your own, along with the must have OG12. If you prefer joining classes or even online courses, you can find some reviews on this forum itself. I have myself taken the knewton complete prep as the 50 point guarantee really interested me and its going on well till now.
So the path you take is up to you. I would then say take periodic practice tests and review yourself. Also try and concentrate on quality not quantity. Its not important to solve 100 problems a day, solve 30 - 40 but review them thoroughly, Go back to the questions you have gotten wrong.
So I would say give the GMATPrep practice test as the first thing and take it from their. You knows you might already be at the 750 level!!
All the best.
A
