A cover letter is essentially a hand shake—your chance to introduce yourself.
Although it is short and to the point, the cover letter is important and it deserves your time and attention. The cover letter should be written specifically for each position because it is critical that the information be tailored to the job you are applying for. In three or four paragraphs, you will state the position you are applying for and how you heard about it, tell what skills you have and how those will benefit the company and declare your desire for a job interview.
Some additional points to remember: