Obtained from an insider look at Penn's admissions process.
Consider applying early.
If you are sure which school you want to attend, going the early route is likely to give you a modest advantage over students with comparable or slightly stronger credentials who apply later.
Take the toughest courses you can handle.
A student whose curriculum includes a good number of advanced-placement and honors courses has an edge over someone with slightly higher grades but a softer curriculum.
Choose your schools well.
The applications most easily dismissed are from those who have not thought at all about why they are a good match for a certain school--and therefore have trouble making a plausible case in their essays.
Ask for letters from teachers who will be enthusiastic about you.
A lukewarm recommendation can help kill an application. Ask teachers whether they can write a strong letter. Most will be honest if they feel they can't give you a rave.
Get to know your counselor.
A tepid, boilerplate recommendation is not helpful. Consider supplying the counselor with a list of your achievements outside class.
Craft essays to the question.
Admissions officers can easily spot "one size fits all" essays. And turn in clean copy that is carefully proofread. Don't rely on a spellcheck program, which won't tell you that Duke appears in the essay you intended for Princeton.
If an alumni interview is an option, do it.
That signals you're serious about the school.
Don't slack off in your senior year.
Admissions committees do look at first-semester grades and have been known to reject students who take it easy.