My wife, who hires people, complains about this point all the time. Unless you've been a serial entrepreneur since age 10, keep your resume to one page. You're too young to have a resume longer than a page.
And if it does not fit, don't reduce whitespace. A light two page layout is better than a dense one pager. And cutting the less interesting parts to get down to one page should be even better.
You probably know this already.. but #1 advice for someone your age, I find, is: don't list "reading" or "swimming" (etc) as an interest to fill space :)
