This first round of editing is tough stuff! I'm making progress - slowly - but getting good comments down.
I'm following someone's advice and have a printed copy that I'm reading to myself out loud and making notes with as I go. I'm about halfway through, then once I finish I'll need to update the "real" copy with all of the notes and comments. It's a real pain in the butt but it's very important; there's plenty of things that I'm finding need correction.
Probably my biggest single issue is repetition. I'll write two paragraphs and use the same word or expression in both, when I should really be going back to something different either the first or the second time. Many of these I'm just noting for now and will update when I put my editing comments back into the computer.