How many letters of recommendation do I need? Although it can vary, generally, you will be asked for three letters. We recommend that you send only the number of letters requested. Admissions committees do not have enough time to read extra credential.
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.