With how competitive the job market is, being able to distinguish yourself in any possible way will help you in the long run. A cover letter does exactly this as the quality of those 3-4 paragraphs will make a difference in you being invited back for an interview.
So, you may be asking, why are they so important? Well, your cover letter confirms to the hiring manager if your background and skills meet their needs, and it also gives the employer a glimpse of your ability to put sentences together. This means no spelling or simple grammar mistakes. Proofread everything!
Here are some overall tips for your cover letter. Do not just have 1 version of it on hand and change the employer’s name and address. You should add your own spark to each one, making it unique and individualized. Your cover letter should also remain concise and should be no more than a half of page.
First paragraph: Open with a reasoning as to why you are writing and the reason for wanting the job. A secret to a cover letter is personalization. Show what you know about the company and how your desired traits fit into the company. How will the company benefit from you and what can you offer to them? Also mention contacts that you know of in the company and who referred you to the position, if applicable.
Second paragraph: This should state your skills and tell what you know about the employer, including information about the position and how your skills fit in to the employer’s needs. Know how you relate to the organization and show that in the cover letter. Whether it is in bullet point form or by highlighting specific projects or experiences, relate it back to the company.
Third paragraph: Wrap up your interests in the position. Also explain what you will do to follow up next and thank them for your time. You want to remain polite, but not be too pushy.
For more help on cover letters and for a sample, check out: http://cnu.edu/ccp/pdfs/cover%20letter%20handout%20-%207-28-10.pdf.