Cover letters are the most important item that you send when applying for a job in higher education. In your cover letter you make the case for why the search committee should favor you for their position.
Here is what you should do:
Restate the position you are applying for and make your opening statement for why you are especially qualified for this job. Do your homework and tailor the letter to the job. Add your basic fields and specializations. If you do not have the Ph.D. in hand, say when you expect to complete your degree.
Also include a summary of current research (put first for research institutions). Work hard on this and pitch your unique research precisely and as ambitiously as your achievement will allow. Add a summary of future research and your teaching experience and interests (put first for teaching institutions). Be specific about what you have taught, how you approach teaching, what you can teach for them.
Remember to mention other credentials and make the case for what you can do for the program. Explain why you are attracted to this position. Ask for the interview and indicate if you’ll be attending conventions. Mention what you are enclosing and what else you can send if they desire more info. If you have a website to showcase your credentials, pass along the url.
Quick advice: Proofread, proofread, proofread. Have 10 people proofread everything you send. It must be perfect. Your letter must stand out. Work on the writing. Eliminate jargon. Explain how you possess the credentials they advertise for. Don’t brag or ladle on the self-importance. Use proper business letter form and address to the person listed in the job ad and/or to the search committee. Be specific and use concrete examples. Avoid vapid statements like “I use a variety of approaches in my research.”
Keep working on and improving your letter!