Decide if you really want to make a living writing. If your primary interest in writing is to give expression to your innermost thoughts and feelings, and you don't really care if anyone reads your stuff or not, that's a beautiful thing. But if your goal is to have great numbers of people pay money in order to read what you write, that's a whole other universe. Most people would say they only want to write for themselves, when what they really want is to be famous for the quality of their thoughts and the charm with which they're expressed. Decide whether or not you want to be someone who writes personal journals, or someone who writes bestsellers. Because they're not even close to the same thing. One is fun; one can be fun, but definitely involves insane amounts of pain. Be clear on your goal going in. You don't want to pack for a day trip and then start up Mt. Everest.
Learn punctuation. (Oh: From here on out I'll assume you want to be a Famous Writer.) It's weird how many people want to become writers who haven't yet mastered punctuation. And mastered is the word, too: You have to know that stuff cold. If you aren't absolutely positive when you can and can't use a semicolon, for instance, then you need to keep studying punctuation until you are. You can't fake knowing punctuation. And you definitely can't write to your full potential without the creative freedom that comes from understanding the most fundamental tool of your trade. (And here's something huge: Learn the rules of punctuation so thoroughly that you know the difference between a punctuation "rule" and a style choice. That'll be a fight you'll fight one day; publishing is filled with people who think the "rules" of punctuation are whatever they happened to learn in the Editing 101 class they took in college twenty years ago. People think there are all kinds of punctuation rules that are really just style choices.)
Work for free. If you're just starting out, write for free. Lots of beginning writers think it's beneath them to write for free; don't be one of them. You need a portfolio, and doing quality work for free is the fastest way to get a good one. Pick your favorite of one of those little free publications in your area -- the kind of neighborhood newspapers and entertainment tabloids ubiquitous in coffee shops and markets -- and study it. See what kinds of articles it runs; learn the word counts of those articles; become familiar with the general tone and style of the publication. Pick one of the shorter types of things the publication regularly features (usually a review of some sort: albums, restaurants, art show openings, whatever) and then write two or three pieces exactly like those. (I started out writing 250-word album reviews for a local free music tabloid, for instance.) Send those pieces to the editor of the publication you're about to start writing for, accompanied by a short, friendly letter introducing yourself (keep stuff about yourself to a minimum: editors are too busy to care). Just say you wrote the enclosed or attached pieces in the hope that they'd use it in their publication (which, of course, you think the world of). Be sure to tell them that you're perfectly okay with them cutting or in any way editing the pieces you've submitted. Just the fact that you're flexible that way puts you in the upper .001% of newbie would-be freelancers, who tend to think their every word is sacrosanct.
Understand publishing. Every publication, from your free local rag to Vanity Fair magazine, exists on its advertising. First publications sell ads, then they flow editorial material around those ads. In a real sense, editorial content is basically filler between ads. The thing about advertisers is that they tend to be unbelievably flaky, which they can do because they know that in the relationship between themselves and the publisher, they have all the power -- which is especially true down at the local level where you'll be starting out. So advertisers come in late with their ads; they suddenly don't like the proof of their ads; they don't pay for their ads; they pull their ads. For all those kinds of reasons and more, publications are forever left scrambling at the last minute to fill space with editorial content that they thought was going to be filled with an ad. This can definitely work to your advantage. If I'm an editor (and I have been, a lot), and I suddenly find out that I've got to fill space that used to be an ad with editorial, you better believe I'm going to remember that stuff you just sent me. If it's clean, and useable -- and especially, usually, if it has a decent picture with it!! -- I'll use it. And I'll be grateful to you, too, because you just became an asset to me. Which means I will be contacting you about future work. So if you really want to maximize your chances of getting published in a particular publication, find out that publication's production schedule. Find out, in other words, what day of every week or month that publication needs to be finalized so that it can be sent to the printer. Advertisers tend to drop out right before a publication's deadline. Make sure your stuff gets to the editor a day or so before it's a sure bet that he or she is suddenly going to be scrambling to fill the space just vacated by an advertiser. That way, when they're panicking to fill that space, your submission, having just come in, will be fresh on their mind, and at the top of their stacked in-box, which'll make it easy for them to get their hands on. In publishing, as in life, timing is everything. Submit your stuff two days before your publication gets put to bed, and rest assured that you couldn't have timed it better.
Learn about word count. Everything about a piece -- being, mainly, its angle and tone -- is determined by how many words it's supposed to be. This piece you're reading right now, for instance, has gone on too long: nobody wants to read a blog posting anywhere near this long. So now I have to end it.
If anyone's interested in my continuing this piece, lemme know and I will. (I can't imagine too many people wanting that; writing is, after all, just a job. And how interesting, usually, is someone else's job? Unless you really are a writer. Then, for some happy reason, just about everyone's job is extremely fascinating. But that's a whole other ... thing.)
Anyway, here's wishing you a wonderful week!