How can you get into MIT?

Being recently accepted by MIT, I can tell you a few things.
1. Apply to MIT (duh). MIT does not use the Common Application, so you have to apply on their website.

2. Note that MIT is a prestigious college with an acceptance rate ~9% for undergraduates. That means you will need a stand-out application. This can occur several ways:
a) having an impressive credential/activity that shows you are capable (e.g. ISEF finalist, USAMO qualifier/winner, published original research, started a homeless shelter, etc.)
b) excellent recommendation letters, preferably from MIT or other college alumni, or high school teachers whom you know well
c) taking and doing well in advanced or college-level courses in high school.

Note that I did not include high SAT/ACT scores. This is because SAT/ACT usually don't predict how well one will do in college. Additionally, lots of other applicants will have perfect or near-perfect test scores. MIT can still reject applicants with 2400 or 36.

With that said, good luck!