Type the reference letter in business-letter format.
Write an introductory paragraph explaining your relationship to the applicant and how long you've known him. Tell the reader about yourself and give the reason your opinion of the applicant would apply to the current application. Establishing yourself as a credible reference will add weight to your letter and to what you say about the applicant.
Mention the job skills, knowledge or qualifications that you feel the applicant possesses in a subsequent paragraph. Clarify why you think the applicant would be a good fit for what he is applying for and back up your claims with examples of how the applicant demonstrated the aforementioned skills and capabilities in the past.
Write about the applicant's social skills in the next paragraph. Talk about the applicant's attitude toward responsibility, his ability to work as part of a team, how flexible he is, how fast he learns on the job, how well he takes direction and about his customer service and people skills. These qualities are all things that many employers and admissions directors look for in their applicants.
Reiterate the main strong points of why you think the applicant should be accepted or hired. List your contact information so that the person reading the letter can contact you if she has any questions or wants additional details concerning things you mentioned in the letter.
Include your title either in your address block at the top of the page or after your name following your closing.