I'm a sophomore: What can I do to heighten my chances?

<p>I'm a sophomore at a single-sex boarding school, and, even though it's about two years ahead, I am really anxious about getting into my top college choices. So this is basically what I have so far to promote myself with, it's not much, but I need some recommendations as to what I should be doing:</p>

<p>Advanced courses:
Took honors algebra II over the summer, skipped ahead to precalculus
Junior AP english
Extra curricular:
varsity soccer, jv field hockey, basketball
Straight A's (freshman and sophomore years)
Piano (5 years)
Also- Starting Mandarin next year
Awards and such
Gold medal for national Spanish achievement test level II
In the midst of publishing a novel (semi-autobiographical)
PSAT: 2130
Summers:
Traveling to Barcelona next year to take courses
Computer Science course level I
COMMUNITY SERVICE:
Organized a few drives (food, books, etc.) for schools and shelters</p>

<p>I feel like I need something that will put me over the top.
These are the schools I'm interested in:
Columbia
UPenn
Brown
Yale (maybe)
Dartmouth</p>

<p>I know I am not even close to getting in to these yet, I need to know how I can get closer!</p>