Your cover letter tells an employer a lot about you, good or bad. Think of it as a sales pitch. It’s primary purpose is to show why your skills and background are a perfect match for the position for which you're applying. It is not the place to present all of your experience, that should already be showcased in your resume.
As your first opportunity to make a great impression, a well-written letter shows that you are serious about your job search. Highlight one or two of your skills or accomplishments that show that you are the right person for this position.
While there is no set format or template, here are some more tips for creating a letter that employers will read:
Keep it brief. Cover letters rarely need to be longer than one page. You can usually sum it up in about four paragraphs:
1. Introduce yourself and explain why you’re writing.
2. Lay out your key skills and accomplishments.
3. Explain why you want to work for the company.
4. Thank the reader, invite him/her to contact you and lay out your follow-up plans.
Personalize. Avoid generic greetings such as "To Whom It May Concern" or "Dear Sir or Madam". Address your letter to a specific person, and make sure the spelling is correct.
Sell your skills. Don’t just rehash your resume. Highlight the skills that are most relevant. Illustrate how they relate to the position.
Clarity is key. Be very direct; write clearly and concisely. Don’t make the reader have to work to figure out why you’re writing or speculate at how your skills match the position.
Be proactive. State how you can be reached and give specific information about your plans for follow-up. Once you've said it, do it; follow through.
Review, review, review. Always take the time to review your letter. Double-check for typos; don’t rely on spell-check. If you have time, ask a friend or colleague to look it over as well. Make your changes and review again.