Thanks for your post. You identify a key requirement in a top application and that is, to make a logical link to your past achievements and your future goals. I can see why a consulting firm would be interested in your experience. you are a classic quant--50 on GMAT math portion and heavy analytics in your career will be helpful when dissecting complex business problems. The consulting world is broad, so narrow your focus to an area that ties into your experience (maybe marketing?) and highlight how valuable you will be to consulting firms because of your ability to break down and quantify measurables and analyze data to hopefully give rise to innovative solutions. By the way, these skills will also be helpful to your classmates in b-school. As an Indian applicant, you will need to focus on how you are different from the average applicant. The typical quant falls short in communication skills, but since you have done work in the marketing field, you may want to play this up as a reason why you have the "total package." Marketing is typically seen as a creative, expressive field, so the combination of knowing this side of business coupled with the quantitative abilities you seem to posess could be compelling.
Hope this helps. Let us know if you require assistance in crafting your story.