Hi.
My profile is as under
Iam from India.
School grades - 83% & 86% in 10th & 12th resp.
UG- 74.4% from NIT-Trichy
GMAT-690
Worked for 34 months with L&T as Marketing executive coordinating All India Marketing and Sales for heavy equipments. Quit to set up a start-up and though the company was registered, could not launch it due to some issues.(14months)
Post MBA I would like to work in the short and Medium term and set up a start up in the long run.
I wish to apply to universities in the top 25 bracket. Will 690 be sufficient.

Take a look at the tier 2 schools at http://www.find-mba.com/board/27082

You should narrow your search by region. Where do you want to go to school, and what are your goals (settle somewhere else or go back to your home country)?

The lower end of the top 25 (Cornell/Johnson or Oxford/Said, for example,) might be in range but I would still consider those as reach schools. Something like IMD or Carnegie Mellon/Tepper might be more realistic.

In general, I think your marketing and entrepreneurial experience might be interesting to admissions committees; it sets you apart from the highly competitive Indian students with higher GMATs who generally come from the tech and engineering fields.