Find out how the college's wait list works. While wait lists are typically a school's way of saying that they liked you and consider you a "runner up," some highly ranked schools use the wait list as more of a courtesy measure. They write to thank you for applying, while never really expecting to admit you. Other schools are more serious about wait-listed students, ranking them and anticipating that they will admit several from the list every year.
Read your response letter carefully. Most of the time, the college provides you with historical wait list numbers and statistical information indicating what the odds are that you'll gain admission. If it's not spelled out for you in your letter, call the admissions office. According to the National Association for College Admission Counseling (NACAC), it is within a student's rights to know where she stands and what the wait list means to her.
Ask the appropriate administrators why you were rejected. While it may be because you did not quite make the grade, it could be because your file was incomplete due to a missing reference or application form. You don't want to miss out on your first choice due to a technicality.
Reiterate your desire to attend the college. Whether you write a note or call and speak with an admissions counselor, respond immediately after receiving your letter. Let the powers-that-be know that you are dedicated to becoming part of their student body and that you are keeping up your GPA and dedicating yourself to extracurricular activities in the meantime.
Update the college's admissions office if you receive honors or awards. While they don't need to hear from you every time they log onto their email, periodic and relevant updates may help your case while indicating your continued interest.
Personalize your efforts. Get the name of the admissions officer in charge of your application so you have a specific name when you call to follow up or give new information.