While a cover letter is important for several careers, a letter of introduction is becoming more popular. Letters of introduction are generally used for more creative jobs that require more knowledge of the applicant's personality as well as credentials.
Use a familiar contact. If you have an "in" within that workplace, don't hesitate to use the person's name in the letter. Make sure to add the name and department that the person works in.
State any experience. Let the reader know that you have some experience. Include any highlights you want to mention or what you have learnt from your experiences.
Include your education. You worked for that education, so make sure your potential employer knows about it.
Mention why you want to work for that particular place. Why is this place on your list of potential workplaces? Tell the reader of the letter.
State your intent. Let the reader know what you have to offer and what you plan on doing in that environment.
Conclude with a creative and respectful goodbye. This is just another way to stand out and show your personality.
Keep the letter conversational. Let the reader know that you are more than just a letter.
Have someone read your letter before it is sent.
Don't repeat all the information on your resume. Come up with new points to mention.