The most important point here is to make yourself stand out, make yourself interesting, and talk about the experiences you have had that have led you to this place in your life where you have this burning desire to do whatever it is you're proposing. It can be particularly useful, while writing and revising these essays, to work with Julie Neff-Lippman, Director of the Center for Writing and Learning, and with professors you have asked to write letters for you, or who have been appointed by the Fellowships office to assist you. Everyone is just as busy as you are, and you are usually not the only one asking for a letter. If you want a good, thoughtful appraisal of your character and abilities, give your writer ample time to work on the letter. Committees want to see that your letter writers know you, in class and outside of class if possible.
Selection committees rely heavily upon letters of recommendation.
A letter that includes specifics about the letter writers interactions with and observations of you will be far more influential than one that just indicates that you've received good grades or repeats what you may have included on the application. It is important for you to cultivate associations with professors outside the classroom. Deadlines are of paramount importance. Materials submitted for campus deadlines should generally be as complete and professional as you would submit to an external review committee. The Fellowship Advisory Committee will review your application, interview you and give you feedback.