It is assumed when an employer states to send a resume that the cover letter will accompany it. Matching the paper and font used on your resume to that of the cover letter will yield the best impression. Take initiative to find out who will be reviewing it. Have someone check your writing to make sure it is grammatically correct and the tone of the letter is enthusiastic but not weak in its content. Having an extra set of eyes review the cover letter helps to insure you are not coming across too arrogantly, too pleading or too vague.
Resumes follow a formatted style and typically only scratch the surface.
A cover letter lets your own expressions and accounts of your strengths for the job shine through. State the name of the position or type of work you are applying for and convey your interest in consideration for the job. Give two or three accomplishments related to the advertisement to illustrate what qualifies you for the job. Be sure to do this in a confident, sincere manner since this letter exemplifies your writing skills. You can also integrate your knowledge of the company here.