Hey there, as mentioned above-I do believe being part of multiple research teams and doing my own independent research was very helpful, I was able to get my name on a publication and attended conferences where I talked to and exchanged e-mails with several professors in ivy league schools. There I was able to develop a relationship with a professor and work in his lab over consecutive summers because of this.

Aside from that you'll need top stats, shadowing, clinical volunteering, etc. (you probably know that). As for EC's I held leadership position in pre-med fraternity and was part of social outreach programs at Bing and did some service internationally. Without getting too specific I also am a blogger and write about my travels.

Getting into a top med school is such a gamble-some brilliant kids get rejected some kids I would think have a slim shot get accepted. The key to success is really optimizing your stats to top percentiles, research, LORs, (all other miscellaneous shadowing/volunteering) and delving into your passions to really strike yourself out as an interesting individual who would add value to the student body. Do what you love regarding EC's don't just go for cliché "pre-med" activities. Many of the students here are English majors, philosophy majors, classical studies majors-they really aim at diversifying. To be desire to a top medical school, its ironic, but don't present yourself as just a pre-med student. Just to give an example-present yourself as an avid writer and traveler with a unique worldview who has decided to go to medical school to address a global health crisis. Paint and craft your applications into a pretty picture.

Sorry I'm getting a bit off tangent but yes I would advise to develop connections with professors, do independent research, and attend conferences and obviously concentrate on grades! Just as importantly, bring out the unique, interesting applicant that you are!