When submitting a cover letter it's easy to fall into the trap of writing a lengthy letter that reads like your resume in essay form. Instead, take a look at these tips to help your cover letter stand out from the rest.
Don't repeat your resume: When writing a cover letter, don't think of it as your resume written out in paragraphs. Since you are already sending your resume along, the hiring manager will have access to your resume. Use the cover letter as a way to let yourself stand out from the other applicants. Try to show your personality so the manager can get a better idea of who you are.
Keep it short: Your cover letter should be no longer than a page, and probably doesn't need to be more than about half of a page. You don't want to risk having the hiring manager not read your entire cover letter. Instead, keep it short and to the point.
Finish on a high note: Make sure the last thing the hiring manager reads in your cover letter is strong. It should be a quick summary of how your experience makes you the right hire for this job.