If a former student or employee of yours has asked you to write a letter for him, you want to get the right tone that perfectly captures what he has to offer. Don't agree to write a letter for someone who you can't speak positively for or for someone you don't know well enough.
Ask the subject of the letter to whom you should address the letter. Get all the contact information. You may address it to "Dear Sir or Madam" or "To the Admissions Committee."
The first paragraph must explain how you know that person and how long you have known that person. Introduce the person and how you can speak enthusiastically on his behalf.
Describe specific situations in which you saw the subject's work. Use examples to show how excellent the person is. You may want to describe a situation that person was able to overcome and how he was able to improve on the job. Be precise and detailed about the person's work. Using examples of the person's work and abilities on the job helps the letter recipient visualize who this person is.
The final paragraph should summarize why you believe the person would be a great addition to the school or company. Thank the committee and personally sign the letter.