Every viable candidate for the most competitive academic fellowships has a high GPA and stellar recommendations. What distinguishes the top candidates (the ones who are invited for interviews) from the others is the quality of the personal statement. It needs to showcase your accomplishments as well as communicate your vision for what you could achieve in the future. Most importantly, your personal statement should make the selection committee members remember you and want to meet you in an interview.
There is no single formula for writing a successful personal statement, just as there is no single profile of a fellowship winner. If you apply for multiple awards, you will likely have to write multiple versions of your personal statement, since different organizations look for different qualities in their candidates. Below are some general guidelines:
Personal statements for graduate fellowships and scholarships differ from personal statements for college admissions. While college admissions committees are looking for academic promise and potential interests, fellowships selection committees expect you to demonstrate professional expertise and insight in the field to which you are applying. For most study and research awards, it helps to think of the statement as an intellectual autobiography that defines a specific academic problem that interests you, explains how your particular work fits within the broader scholarly or professional field, proves your own expertise through detailed descriptions of past achievements, announces what you hope to do after the fellowship, and connects your proposed fellowship opportunity with these areas. In other words, you should tell a story of increasing expertise over time (especially in your college years) that leads smoothly into your plans for the future.
Choose examples wisely. When proving your claims, try to avoid anecdotes that only show the ways in which an event, course, or experience affected you. Instead, focus on examples that show your expertise, your approach to solving problems, your effective leadership, or another trait that you hope to showcase. What have you already done that will make a selection committee excited to invest in your future?
Successful personal statements cannot be written in one sitting or even in one week. Starting early is essential, and early may mean months in advance of the submission deadline. Some applicants write several very different draft versions of a personal statement before deciding which approach works best for them. Show drafts of your personal statement to as many people as you can (with the exception, of course, of awards like the Rhodes and Mitchell, which have rules against this). People who know you well should be able to read your personal statement and recognize that only you could have written it, that it doesn't sound at all generic. People who don't know you well should be able to read your personal statement and understand the major points you want to convey.
Make sure there are no grammatical errors in your essay and that the writing style is graceful by the time you are showing it to a campus committee. Take time to read your essay aloud and edit ruthlessly to avoid clichés and repetition. This essay needs to be representative of your very best work; make sure you give it the time it deserves!