edeevee asked if I would share the revisions process. I can only speak for myself -- everyone has a different way of approaching it, just as everyone has a different way of writing the draft.
For me, the first thing I do is skim the revisions letter. This allows me time to storm off and rant a bit about my otherwise-beloved editor, without actually doing any damage to the process. That usually takes a few hours, and lets me sleep on it.
This also allows me to think "hey, the letter was only five and a half pages long. That's not too bad for a 100,000 word novel. I've given out much worse."
The next morning, pending any other obligations (I've put aside the New Project for now, as the two writing styles are miles apart) I make a pot of very strong coffee, eat a good breakfast, and settle down with a print out of the letter and several colored highlighters. Each color signifies a different part of the letter (in this case: A plot, B plot, Wren & Sergei's relationship, secondary characters, and Other Details).
Then I go over the letter several times, highlighting each section and jotting notes to myself in the margins as thoughts or fixes strike me. This is what I'm doing right now.
This is where the editor earns her gold stars. It's your story, your brain, your responsibility to fix it. However, a good editor can point to what doesn't quite work, both globally and in the small details. A great editor can point to what doesn't quite work and offer some thoughts on WHY, thereby triggering your own critical and creative juices again.
This often leads to a sudden moment of authorial 'gotcha!' which is occasionally followed by either "okay, that bit's got to go, I can't fix it" or "fuck I'm brilliant." The latter moment actually just happened, so I'm taking a break right now to let the fix expand and solidify in my brain. And with that realization, an entire chain of needed plot-fixes fall into place. They're not DONE, but I know what needs to be done.
The doing comes next. But for now, more bits to highlight and hammer at. And more coffee to drink.
ETA: I looooove my editor. Even when I'm cranky. She gives good brain-poke.ETA2: No. More. Coffee.