A cover letter comprises three main elements:

1. Introductory paragraph. The first paragraph mentions the position you're interested in and how you learned of the opening. If a friend or business contact told you about the position, mention his or her name, and be sure to send him or her a copy of your letter. In this paragraph, you may also want to specify why you're applying to this particular company (for example, because of its outstanding reputation in the field). This paragraph is normally two-to-four paragraphs long.
   
   If you are sending a mass mailing to many companies over a large area, in addition to focusing on the type of position you seek, it would also be advisable to introduce some of your abilities that would be of interest to an employer. If you are sending a cover letter to a specific company and don't know whether there is an opening, begin by explaining the type of position you want and why you are especially interested in working for that company.
   
   
2. Body. In the middle two paragraphs, "toot your own horn"-honestly of course. In this section, mention at least three of your strong points. One good technique is to use the first paragraph of the body to explain your educational background and the second to describe your work experience. The more specifics you can list, the better. Also, mention personal qualities that suggest you're a highly desirable employee. Are you energetic, enthusiastic, detail oriented, and a fast learner? Choose adjectives that are applicable to the position you want. Use the body of your cover letter to make a connection to the employer.
   
   If you didn't already mention in your introduction why you want to work for this particular employer, this is the place to do it. Make a clear connection between your skills and the needs of the company. Your careful research about the company should impress the reader.
   
   
3. Closing. Don't forget the overall purpose of your cover letter and resume: to obtain an interview. Be sure to indicate specifically and assertively what you want the employer to do next; for example, "I'd like to arrange an interview at your earliest convenience" is a clear statement. Mention how and where you can be reached, or indicate that you'll call the employer on a specific day. The tone of this section should be polite yet explicit.

Source: From Susan D. Greene and Melanie L. Martel, The Ultimate Job Hunter's Guidebook, Fourth Edition. Boston: HMCo., 2004. pp. 109-110.