There are a few ways you can enhance your candidacy, but some of them may be out of your hands. Here are some examples:
1. If you are able to show that you've improved yourself significantly even once your application is submitted, then I would encourage you to write in and let them know. This probably only applies to promotions. But if you improved your GMAT, or did something else large like that, I would encourage you to write in. These things could slightly help your cadidacy
2. If you think that there is a real chance of not attending bschool this year, especially if you think you'll be denied, I would encourage you to start working on next years application right now. That doesn't mean your essays, but you could start seeing what groups/clubs you could join in your community to help boost your extra curricular work.
3. If you think that your quant ability may be a question mark on your application, you could enroll in a statistics or calculus class and update the adcoms letting them know that you are preparing for bschool. There is also a website called: http://www.mbamath.com
that is known for giving a solid foundation for business students. Also, many colleges that you applied to might recommend certain classes they offer through extensions or other medium that you could enroll in. I would update the Adcoms of your intentions.
At this point it is really just a waiting game. None of these suggestions are requirements b/c they probably won't change your application much, if any. But they're just some ideas if you really think you are right on the edge, or have less of a chance then you'd like.
PS. The only time you should update an Adcom is with something BIG. I would refrain from contacting them at any other time, other then if you have a big update for them. You don't want to be known as the stalker, or annoying guy that keeps emailing/calling.
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