I don't claim to be an expert, but I've been writing 1,000 words a day almost every day for the past 120 weeks. That's the most important tip of all -- to be a writer, start writing. You'll figure out a lot of things along the way.
But for all of you overachievers out there, here are some other ideas that may help.
Move from the general to the specific. Here's the idea, now here is how you apply it. Give people the concept and then tell them more about how they can use it. Travel is fun and meaningful; here's how you can actually book a Round-the-World plane ticket. To stand out in life you have to be awesome; here's what that looks like. Change the world by doing a, b, and c.
Get personal. This is the Penelope Trunk model: often imitated, but seldom to the level of the art form she's made it. A lot of people copy Penelope's tactics without relating them to a broader strategy. You have to have a strategy. She does it right; her imitators do it wrong.
Write for an audience of several. I think of about five people when I write. They're all different, but I try to picture them and think, what would so-and-so think of this? Would he get it? Would she find it interesting?
If it "goes without saying," you don't need to say it. I hate reading that phrase... and when I discover it in my work, I hate it even more. Other overused writing phrases include: the jury's out, think outside the box, it is what it is, and my two cents. Alas, I use them all once in a while.
Always answer the reason why. Why should someone care about what you have to say? Of course your friends and your parents care about what you think, but what about everyone else? You need a clear reason for the rest of the world to care.
Do the second edit later. It's impossible (well, for me) to write and edit anything longer than an email without needing at least a short break. The longer the draft, the more of a break I need.
Print your work and proof it on paper. I used to write in longhand and transfer it to the laptop, which also helped. Now that I do this for several hours a day, every day, I write almost exclusively on the laptop.
Read everything aloud. There's something about hearing your work aloud that causes you to notice things you miss when you read. On our annual review trip last December, Jolie read the entire AONC book manuscript out loud over the course of a week (1-2 chapters a day). I couldn't believe how many mistakes and poor word choices we found! Keep in mind this was after I had been writing the book for six months, and after two complete edits. It was depressing... but hopefully now it's better because we did it.
Get into the details! Don't be vague. Provide more info, work it out, tell the whole story. This makes a huge difference. This is why J.D. Roth is such a role model to me. He always tells the whole story. The Yarn Harlot also does this well.
Take the time to do it right. Ramit told me about how he spends 12 hours writing a guest post for someone. Some people are surprised, but that's how long it often takes! When I get an opportunity to write for a great outlet, whether online or offline, I spend a similarly long time on it.
Preempt objections. This is an important marketing strategy, but it's also important in your writing. Build your case. If you're trying to present a viewpoint, think about what the objections will be, then try to preempt them by addressing them (and often negating them) in your writing.
Take a stand. Contrary to conventional wisdom, readers want to know what you actually think. If consensus is overrated, so is neutrality. What bothers you, and what are you doing about it? Tell us.
Lastly, recognize that any creative act worth doing benefits from an ongoing process of continuous improvement. Writing is no exception. I don't like everything I wrote in the first two years of AONC. Next year I probably won't like everything from 2010. I want my second book to be better than my first, and so on.
That's just how it goes, and you can't improve without getting something out there to start with. That's why the first writing tip is the best: if you want to write, start right now and don't stop.
What would you add to this list?