Competition varies from district... Simply, be involved in leadership, some sort of varsity sport (team sport preferably), and have good grades
I came from not the most competitive district
If I can recall the resume that got me in correctly it was something like this:
Boy Scouts, Eagle Scout award, SPL
National Honor Society
ASB commissioner
Varsity Swimming, Varsity Water Polo
Black Belt in TaeKwonDo
1960 SAT (my parents are still upset at this score

)
3.6 weighted GPA taking around 10+ honors and AP courses. Ranked around 100 of 520 students in graduating class.
Once again it depends on how competitive your district is and this is an example. I am pretty sure there are people who had a much STRONGER academic record than I did. I was the only one from my school who applied and our district only had 8 people who applied to USMA.