Petrula Vrontkis writes a good article on common mistakes in cover letters and résumés, focusing on what not to do (and then how to do it). In particular, I like the idea of never starting with “Hey ….”
Other advice:
“Worked on many projects for local design studios and directly with companies.”
Avoid vague references about your employment experience. I don’t have high expectations of a recent grad in this area. Simply state your title, the name of the firm and its location. Include a brief sentence defining your responsibilities. Don’t give me a long list of the firm’s clients or other “padding.” Stick to what you worked on. Definitely keep school projects, including sponsored projects, out of the “Experience” category.
Beware: Listing a lot of experience, employed or freelance, but not showing any of the work in your book makes me suspicious. I’m concerned that your design approach may drastically change when the project is real. Do include a letter of recommendation if you’ve completed an internship or worked for a recognized design office.
The questions to consider are: What unique experiences have I had, and how will these experiences uniquely benefit this firm? Obviously this requires soul-searching and researching. Both of these are in your job description as a job hunter.”
Emailing a cover letter
Write a short, comprehensible subject line – serious or snappy but not condescending.
Paste cover letter into email, also attach it if it’s designed.
Before sending that cover letter with “Dear Sir or Madam” at the top, go to the website of the hiring company and look for the relevant name. If you are responding to a posted position, address the letter to the person listed in the notice, paying special attention to the way their name is spelled and whether they are male or female. If you are introducing yourself to a company, use the company’s online directory to find the particular person who would most benefit from your design work, and address your cover letter to them. Read articles or blog posts about the company, so that you can write about them intelligently. Do not send a cover letter that merely swaps one company’s name for another, or the design firm will treat you the same way. source.
Some examples: Templates such as the one below.