Cover letters are extremely important additional documents for accompanying resumes and have to be extremely concise and to the point. While there are many different types of cover letters, the ones used most often are those accompanying resumes to prospective employers.
The first most important tip for writing that perfect cover letter is to address it to a person and name him or her in the address part. This personalizes the entire letter and also shows the efforts you have put in for the job. Second part is to express an avid interest in the company and the position. This is very important and something that most people forget to state.
Many feel that cover letters are used to sell the resume and hence should use a good amount of jargon that do not find place in the resume. Qualities like meticulous worker, team player, leadership abilities demonstrated etc should be used in the body of the cover letter to express both experience and achievement. In some cases, it may be a good idea to also mention your qualifications but this is based on the job and the qualification required for the same.
Finally, you should end the cover letter by thanking the person for his or her attention and also leave room for a follow up. This could be in the form of a phone number or a message that you will call and find out.