I am in a unique situation where I have the perspective of a freelancer and an editorial art director. I know what freelancers are thinking when marketing themselves, and I know what makes an impression on art directors. Here's how to pitch yourself to publications...from an art director who works at one.
Do Your Research
Consider the publication type. Don't proclaim "I would be a great fit" unless you can say so honestly. I've heard from people who have clearly never looked at our magazine — their work is not at all in the same realm of what we generally publish. Also, I work at a city magazine; we only use contributors who live in the area or have ties to it (ex. grew up or went to school around here). How well do you really fit with the publication you're after?
Spellcheck the recipient's name. This should really go without saying. Before you send anything, check one last time. My co-worker immediately trashes anything with his name misspelled...as he should.
Make Your Move
Mail a postcard. This is the best medium for marketing yourself to a publication because it's not as invasive as an email; it's personal(ish); and it's easy to save ones we like. Another co-worker and I have inspiration walls by our desks that display our favorite postcards.
Write something by hand. Either address it by hand and/or write a little note. It's more special to receive a postcard that's been handwritten as opposed to one you slapped a computer-generated label on. It shouldn't feel as though you sent the exact same thing to 100 other art directors — even though you probably did. At least put forth some effort to minimize the obvious.
Mind Your Manners
Follow up sparingly. And do not expect a response. It sounds harsh, but put yourself in an art director's shoes: we get the same request from tons of other freelancers. There's no time to respond to everyone. If we want to work with you, we'll tell you. If you are dying to reach out again, send another postcard or email occasionally...like every few months. You already planted the seed — don't overwater it.
If emailing, don't clog up our inboxes. Include one or two low-resolution images. This gives a quick preview of your new work without us having to click through to view your whole portfolio.
If emailing, do not add anyone to an email list without their permission. FOR THE LOVE. Do you like getting spammed? Didn't think so. Do unto others as you would have them do unto you. I know, I know: email lists are an easy way to send follow-up messages about recent work. Fine. At least give people a way out with an unsubscribe button. We didn't ask to be put on that list so spare us the awkward "please stop annoying me" email.
Keep Your Head Up
Remember: If we like what we saw, we'll contact you. It might not be right away. Sometimes we're just waiting on the perfect project for your style.