Open with a short, but enthusiastic, bit of praise. Let the company know right off the bat that you believe in this person. You don’t have to be over the top or insincere, but a positive note to start will make a big difference. It makes me extremely happy to recommend Michael for the position of Director of Development at XYX Corporation. Any company should count themselves lucky to have an employee as bright, friendly, and dedicated as Gina. No matter what she does, Helena Bonham does it well.
Keep your writing action-oriented. Begin each paragraph with a punchy, active affirmation of the candidate’s qualities or character. Strong verbs are your friend.