There are 12 rules that apply for cover letters:

• Always send a neat letter not an email (unless instructed to).
• Be honest and to the point.
• Be unique and focused in your paragraphs.
• Make a personal connection with the target.
• Portray your personality in your communication.
• Target the correct individual.
• Ensure you have some control over the outcome.
• Be concise in your choice of words.
• Be consistent ensuring the phrases are similar to your resume.
• Ensure no extraneous issues are inadvertently included.
• Only one page is necessary (anything longer is too much information).
• The objective of the cover letter is to get you to the interview.