Not just humor, but the overall tone of your application essay is remarkably important. It's also difficult to get right. When you are asked to write about your accomplishments, those 750 words on how great you are can make you sound like a braggart. Be careful to balance your pride in your achievements with humility and generosity towards others. You also want to avoid sounding like a whiner -- use your essay to show off your skills, not to explain the injustices that lead to your low math score or failure to graduate #1 in your class.
It may sound like a chore, and it will certainly take a substantial amount of work. But it's also a unique opportunity that can make a difference at decision time. Admissions committees put the most weight on your high school grades and your test scores . However, selective colleges receive applications from many worthy students with similar scores and grades—too many to admit. So they use your essay, along with your letters of recommendation and extracurricular activities , to find out what sets you apart from the other talented candidates.