Decide if you want to be in the military. The academies exist to create military leaders. All graduates serve in their respective branch of service following graduation.
Get in shape physically. If you do not enjoy physical activity a service academy is probably not right for you.
Follow rules. The academies are very regimented and structured. People who function well in a structured environment do well at service academies.
Talk to current mid-shipmen and cadets. Ask about the daily life at a service academy and try to imagine yourself in those situations.
Visit a service academy if possible. Nothing provides a better idea of what the experience is like than seeing it first hand. See how the students interact, study and have fun.
Get ready for math and science. All service academy students graduate with a bachelor of science degree regardless of major. The academics are strenuous and time management skills are required.
Take on leadership roles. Find out if you enjoy being in a leadership position.