This is how I revise long pieces.
1. Finish book. Let it sit for some reasonable amount of time without looking at it at all.
2. Print out a single-spaced hardcopy. Read it with no line editing- just making general notes like "fix this," "this conversation needs to happen sooner," "cut this?" etc. (Sometimes I do this by sending to my Kindle and reading it there, but it makes taking notes more awkward).
3. Go back and do plot diagramming (see post from Friday). While doing this I take notes per scene that are more specific (eg, "he should be more suspicious here.") or just general notes that only occurred to me just when I was reading that particular scene.
4. This is when I would plan major structural edits-- usually I have something I can physically move, like notecards or post-its that represent individual scenes.
5. Next I make a list of the large-ish things that need to be fixed, drawing from the previous notes, or things I know in the back of my head need to be fixed. (eg, "cut out this character," "there need to be more hints that this person is the murderer.") I don't put in pretty minor things that are confined to one thing only (these are just in scene-level notes.)
6. When I do a revision, I'm only doing one thing at a time. My original approach to revising was to start from page one and think "okay, fix everything." This is too much to handle at once. I heard this "one thing at a time" per revision thing from author Daniel Torday when workshopping with him once. I thought it was a fantastic idea and have been doing it ever since. Cutting out a character from an entire novel is a major thing--a thread that is probably tangled across different scenes throughout the book. It's easier to go through the book only looking for and fixing this one thing--how to cut this character out. I found that it really focused my attention on one thing at a time. I did one revision that was about eliminating an extraneous plotline. Another that was beefing up one particular character. When I do multiple POV things, each character gets their own revision--I go through the book only reading their POV sections, making sure their character and voice are consistent, that they appear to have an arc over time.
7. Final copyedit revision- this involves printing the whole thing out and reading it out loud. This is sort of a pain and hurts your throat, but is worth it. It catches typos and gives you a better sense of when the rhythm of your sentences is off.
8. Save an extra Word and PDF copy somewhere else safe. Save separate Word files that contain only the first ten pages, first 50, and first 100. (It's easier to have these lined up for when you want to send it out to people, as opposed to copying X pages every single time out of your larger document.)