Ask HN: How do you shorten your resume when you have a lot of things to put in?

I'm pretty young, so I guess I should keep my resume relatively short(1 page?)

But I've had 2 full time jobs, an internship, a dozen freelance gigs, 3 schools, maybe at least 5 interesting side-projects, I can't possibly fit everything on one page

How do you decide what to keep?