The soft-focus stuff about why we write somehow escapes me; I feel better when I write and worse when I don't, and the rest is blather. But I love practical advice that improves my actual writing, so I read a lot of books and articles about the craft. I've mentioned Stephen King's On Writing, but of course I also love Card's How to Write Fantasy & Science Fiction, Syd Field's Four Screenplays, Dibell's Plot, and too many more.
A lot of these books even contradict one another: write with an outline, or just go? Bounce ideas off friends or work in secrecy? Edit now or write something else first? Of course they contradict one another. This is an art. You get better by studying and practicing, but there is no perfect.
I just found a blog that I absolutely love from Aimee Salter that is full of practical, useful, hammer-and-nail writing advice. Salter specializes in advice that helps you eyeball your own work for obvious pitfalls:
Seek and Destroy "was"
I've left this one until last because when you go through your manuscript searching for 'was', prepare to be there for a while. And each replace will be a little more involved. In most cases you won't be able to simply delete 'was' because you'll have to change the tense of words around it. But the seemingly endless task is worth it.
In most cases, the change is simple: "I was leaning on the windowsill." becomes "I leaned on the windowsill." Or, "I was faced by half a dozen upper-class snobs." becomes "I faced half a dozen upper-class snobs."
See the difference?
Now of course, you could read that and say, but my sentence really needs a "was", and maybe it does. But these are tools to help get rid of the rest, and set those sentences apart.
I have been writing for a long time, and I feel that only in the past few years have I gotten my legs under me. Exposure to tools like Ms. Salter teaches would probably have helped me, if I had sought them out and had the sense to use them. Check out her Self-Editing Tips and Tricks blog!