A friend of mine was in Admissions at Columbia for many years and had some good advice. So I assume you have the baseline excellent grades and test scores. But how to stand out? Look at what is missing at the school.
My friend said she read through thousands of applications every year where the applicant was a violinist. Problem? Orchestras need only so many violinists. What was desperately needed was a French horn player. Orchestral music scores almost always have the French horn. But she almost never received an application from a French horn player!
Sane is true for Fencing and Squash. Ivies tend to need more fencers and squash players than they have applications from.
Also look at niche majors. Cornell has a fantastic Forestry major but not a ton of Applicants.
Lastly look at what you can Create. Ivies look fondly on inventions, trademarks, patents, something that you felt passionate about and created. The Ivies get tons of Applications from people who worked with the homeless, or in a clinic, or in a food pantry, or off to Africa for the summer to assist in vaccination programs. All outstanding things, obviously.
But show Admissions what you Created, not just what you Joined.
Readers: this advice is solid and highlights one of the difficulties in gaining admission to selective colleges: qualified applicants are a dime a dozen but finding the few who have something unusual is difficult. Fill a niche and you increase the chances of success. Lets talk about your unique opportunities. firstname.lastname@example.org or 610-212-6679.