A cover letter is a glimpse into where you have been, where you are and where you are going on the career path you have chosen. Word choice, in this one page first impression, can make it a smooth or rough ride to the top.
Tell what job you are applying for and how you heard about the opening (newspaper, Internet or referenced by another employee). This is especially important if the company has more than one position available. Accomplish this in one or two sentences.
Describe qualifications, skills and traits that support the position applying for. Highlight three or four credentials that make you stand out above the other applicants. Employers want to know how you will benefit their company; mention what you did to help your last or current company to grow and what makes you an invaluable asset to their company. It is not necessary to list past employers or go over every tread mark on your career path; this is what the resume is for. This five- or six-sentence paragraph should make the employer want to read your resume for further detail.
Mention the enclosed resume and subtly request further contact. The last paragraph should be the employers call to action. An acceptable "call to action" sentence could read, "I would be happy to discuss my qualifications with you in person or over the phone and look forward to hearing from you at your earliest convenience." Do not be demanding and always thank the employer for his time and consideration.
Avoid spelling and grammar errors; this could cause a wrong turn on the career path of even the most qualified candidate.