The thing is this: read your drafts aloud. I'm not talking about learning to perform your work, which I also wholeheartedly recommend. I'm saying that in the privacy of your little workspace, to your own little self, you should read your work aloud. Fiction, nonfiction, whatever. It is astonishingly helpful.
For years I resisted this advice, because it would, you know, make me feel like a dork. It is odd to worry about feeling like a dork even though--or in this case because--no one can see or hear me being a dork. Apparently if a dork falls in the forest, etc., he or she is even more of a dork.
Anyway. My other objection to reading aloud was that it wasn't really necessary. I can *pretend* to read aloud using the little voice that's always yammering on in my head, which is very similar to my actual voice. But that's not true. For one thing, you can't skim when you're reading aloud. You have to say (and therefore read) every word. And boy, do you catch mistakes that way.
But reading aloud is not only important for copyediting purposes. Whatever type of writing you're doing, hearing the sound and rhythm of your words will make a big difference. I read a draft out loud just this morning, and there was this one sentence at the beginning of the last paragraph that went "clunk." When I wrote it, I thought it was audacious and charming. But then it went "clunk." So I thought about it, and realized that in fact it didn't fit. It clunked because it made no sense, and when I took it out, harmony and rhythm and sense were restored.
This is not to say your rhythm should always be smooth. Sometimes you want a word or line to be jarring. But there's good jarring and bad jarring, and bad doesn't just mean the sound is off. Likely as not, the sense is off, too.
I just read this post aloud. I made several changes.