Advice for High School Freshman

I realize that the admissions process is a bit arbitrary, but what is the best advice someone gave you for getting in? I am a high school freshman who is eager in business, econ, and compsci, and I really want to get in. Objectively, I am very competitive; however, I realize that this is not the only portion evaluated. Do any successful applicants have any advice, and could elaborate on it(e.g. not the generic “follow your passions”)?

The best advice for a freshman is think about applying sideways: http://mitadmissions.org/blogs/entry/applying_sideways