The current work-in-progress, The Bone Road, is at the third or fourth revision. By this time, it's difficult for me to stand back and see anything either right or wrong with the story. I'm too close. One way to get around this is to sit in the most comfortable chair I can find and read the manuscript aloud. Slowly. Hitting every comma, paying attention to every voice. An amazing number of errors show up: typos, dreadful punctuation, clunky sentences, homonyms never to be caught by a spellchecker, etc.
Previous embarrassing experiences have taught me I cannot proof the manuscript on the screen at this level. My eyes glide over mistakes. It must be paper. So I read and read, scribbling notes to myself, until I'm too hoarse to carry on. I listen to audiobooks a great deal and reading my own manuscript gives me a new take on the narrators. This is difficult work and I hope those narrators are well-paid.
Fixing all the minor typos, etc., is easy. Every so often I trip over a sentence I cannot make sound sensible. If I cannot read it aloud I'm assuming any reader will stumble also. Those I mark with 'AWK' for awkward and wrestle with later. And sometimes there's that dreaded voice in the back of my head: boring, clumsy, something is missing here, something is wrong. I think all writers learn to listen to this one, primarily because if you don't it tends to return at 3 am until you do.
Unfortunately, listening to the voice telling you what's wrong doesn't automatically tell you how to fix it. Especially when fixing it means unbalancing the remainder of the book and drastically revising the plot. I'm working on a problem now in the second half of BR which I hope can be solved by inserting a new scene and expanding on the motivations of one of my villains. With luck.
It's amazing how reluctant I am to work on this. I can always tell when I am avoiding writing-as-work because my brain starts churning out completely new plots for the next novel or short story. That qualifies as writing-as-fun.
Another good way to avoid writing-as-work is to do a blog post.