Just my input. Remember, I don't write specifically to the poster, but also to those just lurking and wondering about their own application to the academies.
When looking at your high school schedules, it's real simple if you're in a program like the IB program. I say simple, because except for 1-2 electives, you have no choice. Your scheduled is chosen for you. But for those not in the IB program, you need to maximize your schedule. Remember, the academies want to see that you have done the most, with what you have offered. Each school and what they offer is different. But maximize what they have.
Very few schools have sports during the school day, so if you have any free time, then you are not maximizing your opportunities. If you have enough time to take 6 classes per semester, then that's what you do. Of course, each school is different and the layout of the scheduling may only allow less. What I'm saying is, you should never have a free semester unless it's part of a program like the IB program. In high school, my son never had less than 6 classes per semester. Usually 7. If you include time in between for TOK (an IB thing), you could say he sometimes had 8 classes in a semester. Of course, they had "A" "B" days. But if you have free periods, rethink your schedule.
Also, in the 4 years of high school, besides the minimum school/state requirements, make sure that what you take are of higher level. AP, honors, IB classes. At least 2 years (4 semesters) foreign language. At least 1 year (2 semesters) computer classes.
By your junior year, your schedule should only include upper level classes. You should have all your school requirements met without trying. As for electives, if you are doing multi year things like band, stay with it. If you have free periods, put in some more AP or honors classes, even if as an elective.
Some will say you don't need as much language or computers or upper level classes. That's fine, but I won't debate the issue. The point is, if you really want to be competitive in getting an academy appointment, then you need to take whatever classes, sports, activities, etc. that are available to you, and make the most of them. If we see you had time, and didn't maximize it, that doesn't look good. Even if you have a 4.0gpa. Part time jobs are good too, but not if you are getting out of school 2-3 days a week at 1pm. You could be taking more classes. Best of luck.