Cover letters will make or break your resume because it is the first thing that is seen before anybody even peruses the attached resume.
The perfect cover letter is supposed to be professional, brief and to the point without leaving out anything important.
The objective of a cover letter is to state clearly why you are the best person for the job. This means that qualifications and past experience that is directly related to the opening must be included in the cover letter.
Many times the person going through the applicants will never get past the cover letter and onto the attached resume. That is how important the cover letter is. This further emphasizes the fact that your cover letter must whet the person's appetite and create enough reason for them to want to move on to your resume with interest. If this does not happen then your cover letter has failed to accomplish its' objective.
The cover letter must be well written and free of typos and grammatical errors. Remember that the person sifting through loads of resumes is looking for the least excuse to toss as many as possible of them into the trashcan. Obvious typos and grammatical errors are clear evidence of carelessness, which means that the applicant will hardly be suited to the position being advertised.
Then your cover letter has to stand out, so you require a little originality and your personal style should clearly be evident.
The final cover letter essential is that you should not forget to sign it.
More cover letter essentials.
Source: www.articlesbase.com