International student accepted to Princeton, Harvard, Columbia, and Caltech

@idsl1996
How he can do to bolster his application
SAT I (breakdown): 2350 (superscore)
SAT II: 800 (Math 2), 800 (Physics)
School Type: Public, ranked 1st nationally, best mathematics school in Ukraine ( Each year we have more two students participate in IMO, the 2015 IMO contest his classmates won one gold and the other - silver)
Won different prizes on national and international levels in Math and Physics.
He has worked as a Math tutor for young students
A team member of school volleyball and football
Spent all his summer holidays at Math camp
Wants to learn to play the guitar
Loves Rock
Any advice or guidance would be greatly appreciated!!!