Okay, I have exceptionally good advice for writers all the time. I write the best possible advice, all day, every day.
Kidding, obviously. But I truly believe this is excellent advice. (So excellent, I'm following it myself.)
Advice here: I strongly strongly recommend that every writer take a line editing or copy editing class. You'll learn so many things about what editors look for in trying to improve manuscripts and how they go about suggesting improvements, and even about why that marked up page looks the way it does.
Writers are amazing. I know how scary difficult it is to write a book, because I have been trying myself. So, props to all writers who have the gumption to complete even one draft of a novel.
Now once you're done, it's tough to finish that draft and then come back and look it in the eye, flaws and all. But when you sit down to edit, it'll be easier if you have a few "real editor" tricks up your sleeve to help you along the way. Knowing even a little about the editorial side of things will make you a much better critical reader, especially once you sit down to revise.
After spending two days in an editing workshop here (with more to come), I can say I am going to be looking at my drafts with a much more critical (and I believe much better) eye. So if you come across a good one, take a class. They are totally, totally worth it.