The first thing you need to determine is whether or not your scholastic credentials are of the highest caliber. As a general rule successful applicants have GPRs of 3.7 and higher. If you have a 3.5 or 3.6, you might still be competitive. If your GPR is below 3.5, you're probably out of the running for most of these awards unless you can demonstrate special talents or strengths in other areas such as leadership and community service.
While exceptional scholastic performance is indeed a necessary condition for serious consideration, by itself a high GPR is not a sufficient condition. To a selection committee there are many factors just as important as your academic bottom line. A student with a "competitive" GPR (say, 3.6) who can converse comfortably across a broad range of topics should be able to compete with a 4.0 student who knows a great deal in his or her field but little else. Also, a perfect GPR can serve as an invitation to closer inspection, especially when intensive in-person interviews are part of the review process. Selection committees sometimes approach 4.0 candidates with a bit of suspicion. They may want to know what's behind and beyond the transcript. Is the 4.0 real? Or is it the result of taking light course loads and otherwise playing it safe?
To qualify for the Truman Scholarship, an exemplary academic record must be matched by strong evidence of community involvement and a genuine commitment to serving others. The Truman Foundation reports that applications packed with extracurricular activities, memberships in clubs and honorary organizations, and student government offices are quite common. The candidate may look good on paper but will fail to advance in the competition if leadership experience is limited or if the candidate exhibits a narrow, self-centered view of public service. As the Truman Foundation states in its information bulletin, successful applicants are "people for whom the 'bottom line' is to make a difference, not a dollar."
Most overseas awards (such as Fulbright Grants) require language proficiency; a deep, sensitive understanding of the host country's culture; and evidence of adaptability to a foreign setting.