I had a question from a reader about the editing/proofing process. A lot of how this works depends on the publisher, the editor, the book, and how much time there is before publication. I'm sure there are rush jobs with big-name authors where they know the book will sell well anyway and they're losing money with each day it's not in print that have minimal editing -- just run that sucker through spell check and go. A smaller press with an editor who only does a few books a year may do a very detailed check every step of the way. I've had books where I didn't see anything from the editor from the time I turned in the manuscript to the time the book was in print, and I've had a book go through four rounds of edits with the editor, then copyedits, then proofing of the typeset pages.
A general standard seems to be that the editor does at least a line edit -- sometimes tightening pacing or revising a scene but not necessarily changing the story while also adjusting wording, as needed. The author gets to see these notes and is the one to actually make the edits based on the suggestions. The manuscript then goes to a copyeditor, who checks for grammar, spelling, punctuation, continuity, house style (if there's more than one right way to do things, which right way does this publisher use?) and general flow (repeated words, clarity, etc.). The copyeditor also puts in the code for any type treatment like chapter beginnings, italics and special characters. The author gets to review these edits and accept them or argue with them. Sometimes the author may find another way to make the suggested correction. At this stage, the author can still make other changes that might come up. This is really the last phase where actual "writing" can happen. These changes are then incorporated, and the book is typeset. At that point, the book is proofread by a professional while the author also gets a copy to review. Here's where they check to make sure the copyedits were inserted properly without messing something else up (and if the edits were done by hand on hard copy, sometimes mistakes creep in because of handwriting issues). The proofreader also looks for awkward line breaks, bad hyphenation on line breaks, too many hyphenated line breaks in a row, "widow" or "orphan" lines (awkward paragraph breaks between pages), and this is one last check for stuff like grammar and spelling. Sometimes there are things that only come up once the book is typeset -- like there might be a small, common, "invisible" word used twice in a paragraph, which usually wouldn't be noticed except when the words line up perfectly two lines in a row in the typeset version. The author may or may not see what the proofreader does at this point, and the author is strongly discouraged from changing anything that's not an actual error (no rewriting). Then there may be one more check to make sure these edits don't mess up something else.
I find that seeing edits is very educational for me because it gives me something to look for in editing myself. One thing to look for is repeated words. I don't think it's necessarily a crime to use some words more than once in a paragraph or on a page, especially if they're smaller, common words and if writing around the use of that word would actually be more awkward and obvious than repeatedly using the word. One I've run into is "out" and "outside." There's not really another good way to talk about where the things happening on the other side of the wall are happening. You look out the window or go out the door to see what's happening outside when you hear noise coming from outside. Still, it's worth pausing to think about in case there is a way to reword it.
Then there are your personal pet phrases or words. Sometimes they're unique to the particular book because of the situation, relationships or voice of your narrator and sometimes they're your own favorites. Look for words that seem to come up a lot, then do a search for them and see if you can find other ways to express those thoughts. There may be things that need to repeat -- a character's catchphrase, for instance -- but you still don't want to overdo it to the point that it gets annoying. I keep a list of words I tend to overuse so that I'm more conscious of them in the future and know to search for them.
Make sure the word you're using means what you think it means -- if you're at all unsure and are using a word that you've seen used elsewhere and have figured it out in context, look it up. Also look for typos that make words -- I seem to have a bad habit of typing "thing" when I mean "think," and vice versa, and spellcheck will never catch that.
I still think that reading a manuscript out loud is one of the best ways to catch a lot of these things -- you'll find awkward phrasing, and it will be more obvious that you've repeated words when you actually hear them out loud. That's also given me some of the reasons I've argued with an editor because the way they change it doesn't fit the way it should sound when read aloud and it doesn't fit the character's voice.
And you have to get used to the idea that no matter how precise you think you are, no matter how careful you are in editing your own work, someone will find an error. Even after multiple levels of other people have gone over it, a new person looking at it will still find errors. And after all this editing and proofreading, there will probably still be an error or two in the finished book (that some reader will kindly e-mail the author about). This is a business where perfectionism helps, but it will also drive you insane.