Student Exchange Programs

I am a sophmore at one of the best highschools in the country. I am in all honors classes & have all a’s except 1 or 2 b’s a semester. Last semester my GPA was 3.6 unweighted & 3.9 weighted. This semester mine should be higher. I started a make-a-wish club at my school and have almost granted a child a wish! I am also a cheerleader for my school year round. I am in a international thialand club were I am a student ambassador to foreign exchange students. I got back my psats and without studying i did pretty good. Although I dont remember my exact scores. Is Duke to hard for me to get into? If so, what can i do to improve my chances?