Introduction to the Program
Preparation in the longer term is twofold. First is taking the courses to provide you with the background to qualify yourself to pursue your dreams, the type of specialization that becomes your major. Second is becoming involved in community & service activities with a view to, if not leadership, then taking initiative to demonstrate a contribution to society. You don't have to help at a soup kitchen, but you do need to be active in the world, fully involved in life, society and community. It is not enough just to be a member of an organization. You need to be a mover and shaker. If you haven't done a huge amount of community service, then you need to have "published a book, started a small business or discovered a new strain of bacteria" while in college. Perhaps not that grand but something pretty much along these lines (for British Isles fellowships) or not as spectacular (for other post-bacc fellowships). Undergraduate fellowships seek less. It is not so much the groups you have belonged to as what you have achieved. You want results to show for your efforts, standout accomplishments that separate you from the norm of simply having been involved in a list of activities. This can depend on how you see yourself, and the skill it takes to highlight such boosting factors in your resume. While substance is paramount, self-presentation is significant, from resume-writing to personal statements and interviews.
More immediate preparation in the year leading up to the application year is to familiarize yourself with the application requirements and the different statements you will write and obtain.
If you desire to excel and be in the forefront of your field or to be a change agent in society, act now to secure an effective & meaningful life. Read the individual fellowships' websites for in-depth information, and the profiles and biographies of previous fellows for insights into what it takes, what you need to do with your life to become a FELLOW. All applicants study the Truman (and Fulbright) sites for general tips on how best & how not to tackle the process. Even where the specifics don't apply to your fellowship, these guidelines get you thinking the right way about how to prepare to complete all fellowship applications.
You can apply for more than one fellowship in the same year provided you begin early enough.
Preparing for fellowships is an educational experience that will serve you well. Preparation for one is preparation for another, as well as for graduate or other programs and occupations.