Although the U.S. Student Fulbright program has several types of grants, the general requirements for writing recommendations for the program may be applied to any of the types of opportunities.
First, the rules for writing any recommendations apply: the letter should be specific about your relationship to the student, and the length of time you have known them, and offer a candid and detailed assessment of their abilities. The most useful general rule I can give you to guide you as you write for the Fulbright is that the program is both academic and ambassadorial, and the program takes both functions very seriously. We will be sending our students out as individual scholars and teachers, and as cultural ambassadors who we believe will have a productive experience and be good representatives of Willamette, of their home communities, and of their country.
Below are a number of samples: