Most cover letters are addressed to people you don't know, so let's just stop referring to them as cover letters since what they really are is sales letters. You are trying to sell yourself to a stranger.
The best way to think about this letter is in terms of direct mail, so pay attention to the well-funded, unsolicited offers you find at your doorstep. Many of those envelopes have been created by the finest writers in the direct mail business.
Here are eight rules from the direct mail experts that should guide your cover letter writing:
1. Open with a bang.
This is the line I used to write: “I am writing to apply for the position you advertised blah blah blah.” But DUH, of course you are writing to get a job. Why else does anyone write a cover letter? So use your first line to sell yourself and make yourself stand out. For example, “I think your company can use my exceptional sales skills and ten years of experience in your industry.”
2. Be clear about your purpose.
Your cover letter is the introduction to your resume. If your cover letter is longer than a page then it is likely longer than your resume, and who ever heard of an introduction that is longer than the main event? Also, write a separate letter for each job, because each sentence of your cover letter should be specifically relevant to the job at hand.
3. Use your time wisely.
A hiring manager spends ten seconds on a resume to decide if she'll reject it or not. This ten seconds includes your cover letter. Don't let your cover letter waste your ten seconds. The rule of a resume is that every single line of the resume sells you. This is true of the cover letter, too. In fact, it's shorter, so it should sell with more punch. Every sentence of the cover letter should give a specific reason for hiring you because you never know which sentence will catch the reader's eye during your precious ten seconds.
4. Format strategically.
Bullets work well in a cover letter to highlight your relevant achievements immediately. Odd numbers of bullets are proven to be easier to read than even numbers, so use either three or five. Seven is too many — the list will look so long that people will skip it.
5. Tell the reader the next step.
A cover letter introduces a resume and the point of the resume is to get an interview. So in the cover letter say flat out that you want a phone call or an email, because that's how someone sets up an interview. This call to action makes a nice last paragraph.
6. Say it, and then say it again.
Put your email address and phone number at the top of the letter, and on the bottom, too. The hiring manager should not have to hunt for your contact info because each second of that hunt is a second the person could change her mind about calling.
7. Come back to it.
If you copy and pasted and have the wrong company name in your opening sentence Spellcheck won't catch it and probably neither will you because it's very hard to catch errors when you've been rewriting the same letter for an hour. So come back to the letter in two hours, proofread, and then send. You'll be amazed and grateful at the errors you catch.
8. Follow up
You have to. I know it is a discouraging call to make because the odds are that you won't get through to a real person. And if you do get through to a real person he will give you no information. But there is a very slim chance that you will get someone on the phone who will take a good look at your resume just because you called, and that will get you the interview. That's why you need to make the call — because it just might work. Besides, picking up the phone is a lot easier than finding another job opening and writing another cover letter.