Rumors of the death of the cover letter are premature. Cover letters often do make a difference – especially if they have all 10 of the following advantages.
1: The name of the hiring manager,
if at all possible, even if you're sending it to Human Resources. And do send it directly to the hiring manager as well! Finding the name and email address of that person may take a little web research – the company website and LinkedIn are the first places to try – or it may be as simple as calling the main number and asking.
2: An attention-getting opening.
What do you think is the #1 most interesting or impressive thing about you, from the point of view of the employer you're writing to? Start with that. Or figure out what their pain points are, and start by presenting yourself as the solution to their problems. Either of these approaches would be much more effective than "I am writing to express my interest in the blah blah position. My resume is attached."
3: Your Key Selling Points.
Emphasis on what you most want employers to notice – the top three to five reasons why they should hire you instead of someone else.
4: Evidence that you are especially motivated to work for them:
Do some research and mention what you discovered that makes you a good fit.
5: Correct spelling, grammar and punctuation.
Even professional writers have their work proofread before publication. You can get good professional proofreading for around $5 per page.
6: Brevity. Keep it to one page or less for mailing, or one email screen (without scrolling).
7: The right format.
Email: Your cover letter should be the email itself, not an attachment. Include the job title in the subject line, plus if possible a few words emphasizing a key selling point. For example: " MBA w/ Global Experience – Region Director Opening." If you're starting from a template, make your changes before pasting the content into the email. Content inserted after that point may appear to the recipient in a different font than the surrounding text.
Hardcopy: Use standard business letter format. Include a "re:" line referring to the job opening. Example: "Re: Region Director role"
Cover letters often end up in the human resources department's applicant tracking system (ATS) along with their resumes. An ATS is like a database that stores applicant information. HR personnel do keyword searches of these materials to determine whose resumes they want to read, and whose to ignore. Your cover letter and resume have more chance of being read if they contain crucial keywords such as the job title being applied for and words describing the most important skills and qualifications for the job.
9: Your phone number.
Even though you phone number is presumably on the resume, include it here as well.
10: In the copy you send to the hiring manager, a promise to call him or her to introduce yourself.
(Of course, this presumes you've got their name and a phone number, and that the job announcement did not forbid you to call.) If you're able to do this, write something like "Because there is such a strong fit between my background and this role, I am going to take the liberty of phoning you Wednesday afternoon to personally introduce myself and answer any questions you may have." Then be absolutely sure you make that call at the stated time, fully prepared (with notes) to effectively handle any response, whether it's "I'm afraid I don’t have time to talk. I want to just let HR handle it," or "I have some time. Tell me about yourself."
Many employers do read cover letters. Make sure yours includes all of the above so it - and you - will stand out.