There are many types of CCA in schools. Some are competitive CCA
(eg. sports) while others are just classified as Interest
Group like dance. CCA is mean Co Curricular Activities, it's a
statement to show you have attended meaningful activities while
you're in your student's life.
I may be very wrong to say this... students who are from
competitive CCA group who have great sportsmanship and won
awards are slightly more valued than those who hold
regular CCA.
The best way is actually to be part of the school team and help
the school win awards, if not at least help participate in events.
Many of us aren't sports people, but just
hobbist. You can find an Interest Group which have your hobby and
work from there. The key word is 'participation'. If you can
win awards, that's bonus for you. Leadership role adds nothing more
but a *shine*.
You heard of Community work and Non profit organization? I
know at least one close friend who wanted a place in
university so much that she did community work regularly apart
from school work and CCA. 
