Inform yourself about the person you are recommending. Spend some time talking to them about their goals and the position they are applying for. Gather together their current resume, any memos or notes you may have on them, and any other information that will help you as you write the letter. The best recommendations are thorough and specific, and having all the information at hand will make the process much easier.
Why should I use the Letter Service at the Career Center? If you are applying to more than three schools, or you think you want your letters held for other opportunities (like law school) in the future, you should plan to use the Letter Service. Your letter writers will write one letter and fill out one form, rather than filling out a different form for every application.