One piece of advice—one that I haven’t seen mentioned—immediately follows from this: The way to improve your writing is to practice writing. Serious prose writers write every day. Academic social scientists who want to write well should do the same, and this especially holds when carrying heavy teaching, administering, and research loads. Because no one generates enough primary research to fill a solid hour of writing every day, it means writing for other audiences. Book reviews, referee reports, recommendation letters, blog posts, it probably doesn’t really matter, so long as the focus is on the act of writing.
I agree with Tom. If you are an academic and you care about more than just painting by numbers — that is, if you care about more than just getting tenure and making a comfortable living — you should aim to have an impact.
If your writing sucks, you might have one of the best contributions ever made to your field, but no one’s going to read it, it will not get cited, and you will not have had any impact.
The solution, as Tom points out, is to start thinking of yourself as a writer. And what do writers do? That’s right: Writers write. Every single occasion you have to write is an occasion to polish and improve your writing. There is no reason why every email, letter of recommendation, referee report, grant proposal, journal article, etc. cannot be an occasion to improve as a writer. All those activities can contribute to making you a better writer — if you let them.
But what is the mark of a good writer, you might ask? A good writer is one who is actually read by his would-be readers. As I always tell my students: If I start thinking of other things I’d rather be doing midway through your essay and you lose my attention, you have failed as a writer.
To see this, pick up any copy of The New Yorker. Their writers write so well that they can get you to read 5,000 words on just about any topic in which you might have had zero prior interest. If you can manage to do this with your academic writing, your academic writings can only get published in better journals and by better presses. Just like no seminar audience will ever fault you for being too clear, no reviewer will ever fault you for writing too well.