I recently finished reading a book--quite a good book, in fact--that could have been so much better if it had been proofed by someone who didn't know the backstory, and who was reading for continuity. I could tell where things had been cut, reorganized or inserted. I'll bet I could tell you the exact page and paragraph.

Several authors have mentioned to me that one thing is that critical to a book is that during editing, the author keep in mind and look for situations where there are references to things that are no longer included (for whatever reason) or for dialog that follows up on something that never happened. So the reader isn't left wondering, "What the heck is going on?"

Speaking of dialog, one of my pet peeves happened in this particular book. The characters were speaking to one another, back and forth, and because I wasn't counting quotation marks at the end of paragraphs or some such thing, I lost track of which character was making which comment. I had to go back and count: character 1, character 2, character 1 and so on. Would it have been all that difficult in the middle of the conversation for one character to refer to the other by name or rank, just to keep it straight?

And my third comment goes to the use of metaphor and simile. Sure, as an author, you want to avoid the dusty, dull old cliches--she was as stiff as a board; he was so hungry he could eat a horse--that type of thing. But the use of phrases and clauses which are so outlandish that they bring the reader out of the story with a "thump" to pay attention to some phraseology the author cooked up detracts from a good story.

In sum,
1. Keep the continuity clear for readers who don't know the characters' history.
2. Keep the dialog clear as to which speaker has the floor.
3. Keep the types of expressions consonant with the mood/setting/characterizations of the story, so they don't jar the reader out of the world the author has created.

It says a lot for the quality of the writer's work and the strength of characters and plot that I enjoyed the book anyway and will buy--and read--the others.