Writing a cover letter is fairly simple provided you put in a little effort to understand what is absolutely necessary and what the pitfalls are.
After the initial addresses, comes the body of the letter, which can be divided into three parts, namely, the reason and interest, experience and achievements and finally the follow up. It is important to express interest in the job and also state the reason for writing this cover letter.
After you have done that you have to match your experience and qualifications with those required and present it in such a way that the employer feels that you are the best candidate for the job. You have to include various jargon like “excellent communication skills", “demonstrated leadership qualities", “team leader and player" etc. in the body of your cover letter, of course ensuring relevance to the job at hand.
Finally you have to end the cover letter by thanking the person for considering the application and you can either leave your contact number, expressing hope for an interview or in the alternative state that you will call after a certain period.