Deerfield and NMH waitlisted... help!

<p>I applied to boarding school next year for the 10th grade (I'm a 9th grade boy), and I got waitlisted at two schools- Deerfield Academy and Northfield Mount Hermon.
Would someone tell me what are my chances of acceptance, and what should I do to improve my situation?
I'm going to send them a letter later with new ssat scores and a few credentials that I've stocked up since applying.
Is there anything else I could do? Please help!</p>