So, is there a secret formula?—No. And to think so will make you one of the "cookie cutter" applicants, meaning you did things to just check off boxes and such. However, besides passion and a genuine love for medicine and for learning, there are some things that are basically vital for applying to medical school. First and foremost grades--get As and Bs. Now while a high GPA won't guarantee you admission into medical school, a low GPA will almost certainly keep you out. Keep your grades up. Along those lines, the exact same goes for the MCAT. Study your ass off for it. It's important.
Now besides grades/MCAT, what medical schools really want to see is a genuine drive to become a doctor--whether that be clinical experience (direct contact with patients), research, and shadowing. Medical schools especially want to see clinical experience and shadowing--they want to really know that you know exactly what you are getting into and that you're ready and want it.
Other than that, do something that you're passionate about that you can talk about in an interview. If you love something, when you talk about it it will come across and genuine and it will be a good EC. If you're just saying things because you think they want to hear it, they will know. They have interviewed thousands of people and they've heard every answer ever. Be passionate. Be genuine.