I’d recommend looking at past decision threads and figuring out what Exeter Admits had in common but, that could only tell you so much. Great test scores, and excellent grades are one thing but, in my opinion (and experience), it’s the essays and recommendations that really pushes an applicant towards success.
Work on your writing and story-telling skills and craft the greatest personal narrative you’ve ever written. Also, find a way to implement what you’d bring to the school within your essays. That, and glowing recommendations (which you have no control over) would boost your chances.
Other than that, there isn’t truly anything you could do. Just try your best to demonstrate who you are and why you should be given an opportunity to attend.