All cover letters should:
Explain why you are sending a resume.
Don't send a resume without a cover letter.
Don't make the reader guess what you are asking for; be specific: Do you want a summer internship opportunity, or a permanent position at graduation; are you inquiring about future employment possibilities?Tell specifically how you learned about the position or the organization — a flyer posted in your department, a web site, a family friend who works at the organization. It is appropriate to mention the name of someone who suggested that you write.
Convince the reader to look at your resume.
The cover letter will be seen first.
Therefore, it must be very well written and targeted to that employer.Call attention to elements of your background — education, leadership, experience — that are relevant to a position you are seeking. Be as specific as possible, using examples.
Reflect your attitude, personality, motivation, enthusiasm, and communication skills.
Provide or refer to any information specifically requested in a job advertisement that might not be covered in your resume, such as availability date, or reference to an attached writing sample.
Indicate what you will do to follow-up.
In a letter of application — applying for an advertised opening — applicants often say something like "I look forward to hearing from you." However, if you have further contact info (e.g. phone number) and if the employer hasn't said "no phone calls," it's better to take the initiative to follow-up, saying something like, "I will contact you in the next two weeks to see if you require any additional information regarding my qualifications."
In a letter of inquiry — asking about the possibility of an opening — don't assume the employer will contact you. You should say something like, "I will contact you in two weeks to learn more about upcoming employment opportunities with (name of organization)." Then mark your calendar to make the call.
http://jobsearch.about.com/od/coverlettertips/qt/cover-letter-mistakes.htm
Email Subject Line Examples
General Salutations for Cover Letters
Cover Letter Salutation Examples
Date
Name
Title
Organization
Address
City, State, Zip Code
Dear Mr./Ms. Last Name:
I am interested in the Coordinator position advertised on XYZ. My resume is enclosed for your review. Given my related experience and excellent capabilities I would appreciate your consideration for this job opening. My skills are an ideal match for this position.
Your Requirements:
My Qualifications:
I appreciate your taking the time to review my credentials and experience. Again, thank you for your consideration.
Sincerely,
Your Signature (for hard copy letter)
Your Typed Name