Editing (aside from proofreading) is really fun. Every draft is basically an alternate timeline or reality where something changes, and it creates entirely new outcomes. It’s kind of like those Dark Pictures video games— most, whoops my bad, SOME— choices you make create different outcomes. An alternate reality, so to speak! Except I don’t make needless twists that ruin the narrative and the entire reason people came to experience that piece of fiction.
Anyway, when editing your book: the biggest thing you’re looking for (in my opinion) is, “Does it make sense?” An example of this is my favorite character, Chiyo, in my book Agony. She was always meant to be the sensitive character of the group… She wasn’t like the others, she was fearful, couldn’t stand up for herself— but because she was so different from everyone. She gave them an outside perspective and a heart. At least to me, that’s who she is supposed to be— In the first draft, however, that was not the case. Chiyo was basically a toxic girlfriend by complete accident in the first draft. She gaslit Claire, blamed things on her, wouldn’t hear her out, and when she would vent her side of the story: it always sounded like Claire’s didn’t matter.
Another example is that in the first two drafts, Claire was unnecessarily mean towards her best friend. Somehow, I had created this strange thing between them where Rachel had done something that made Claire permanently pissed off at Rachel and untrusting toward her. I’m not sure how I did that, but these two examples are clear reasons for the mandatory process of editing your book. You need to read through everything you wrote and check if the conversations line up, if the undertone is correct, “Does it make sense?”
When working with someone else and getting help to edit, I would say: check what they’ve done before to get an idea of what they’ve worked with. I have only ever truly worked with one editor, as the others only helped proofread, so my editor is easy to work with because we know each other. She understands what I’m going for and doesn’t take the wheel, just completely changing things willy-nilly regardless of my vision for the story. She helps find what I’m looking for. So, getting to know your editor (I would say) is essential. Find someone who has experience, see if you can find examples of their work, and then talk to them. Try to explain what your work is about. The more they know about you and what you enjoy doing, the easier it’ll be to get on the same wavelength!