Use standard formal letter writing conventions to begin. A letter of recommendation is like any other professional communication, and follows the same general rules and guidelines. Place your address on the top right, followed by the date—spelled out. Below that, on the left, place the recipient’s name (if known) and address. Open the letter with a formal business greeting. Ex: Dear Ms. Smith, Dear Sir or Madam, (if you don’t know the recipient’s name)
It’s always a smart idea to offer to write a letter of recommendation for a colleague who you know is well qualified for the job in question. Consider it good career karma; after all, you never know when you’ll need a letter of recommendation for yourself, and your colleague may be happy to return the favor.