When requesting a letter of reference from a former employer, address the employer by his formal title, and begin the letter by asking if he feels comfortable evaluating your work performance. The letter should provide the employer with details about your work history.
In addition to providing details about dates and duties of former positions, provide the employer with information about personal and professional accomplishments that pertain to the desired job. Close the letter by thanking the employer for his time, and include a specific deadline when the letter is needed if he is willing to write one. Provide an address or email address to deliver the letter of reference.