Generally, take a well rounded high school college prep schedule, but pay particular attention to math, CS, and physics courses:
Math: highest level you can reach (precalculus if you started with algebra 1 in 9th grade, calculus if you started with algebra 1 in 8th grade or earlier); statistics is optional but not a substitute for precalculus or calculus
Science: all three of biology, chemistry, and physics (especially physics)
English: four years
History and social studies: three or four years
Foreign language: level 3 or higher or equivalent; super-selective schools tend to look more favorably on level 4 or higher in a non-heritage language
Art and/or music: yes
Academic electives: include a computer science course if available