According to "College Application Requirements" at the College Board website, many private colleges require students to provide them with letters of recommendation. Teachers and guidance counselors are ideal people to ask for letters, because they know you in an academic setting. Make sure that you get letters from teachers who will write strong letters providing positive information. When you ask for a letter, pay close attention to their reaction. If you sense hesitation, reconsider asking them.
Some private colleges require students to take part in an interview. Even if the school you're looking at doesn't require an interview, ask to have one with the admissions counselor. This, in addition to visiting the campus, will reflect positively on you. If you cannot make it to the campus in person, ask for a phone interview. If admissions counselors will not agree to an interview as part of the admissions process, try to ask them questions over the phone anyway. You can gain important information that will help you prepare a noteworthy essay.
According to the College Board article "College Admissions," very selective private colleges look at student essays to determine whether the students should be admitted. Include your philanthropic efforts in your essay to display your best side. Demonstrate what your goals, dreams and accomplishments are, to reveal your organization skills and motivation. Writing about your impressions of the school is also helpful. Read your essay aloud, and have a teacher and a family member provide feedback and proofreading.