The other major question(s) my friend had about revision was: how do you know what needs to be done? And how do you know when you're done?
Okay, so: what you're doing, in general, as a writer, is: you're cultivating taste. You're cultivating your taste. I don't mean that you're shaping your taste to an external standard of The Canon, although you can do that if you like. I mean you're figuring out what it is that you like and how it's achieved in practice.
You can skew your taste a particular direction--Hugo nominees, say, or stories published in a particular magazine. But you pay attention to what you're reading, what you like about it, what you notice about it and don't notice. You look at sentences, paragraphs, chapters, sections, books, series; poems, short stories, novels, travelogues, articles, all of it. You see what grates on you, what makes you wander off, what compels you. What do you like. And how does it go.
So then when you're looking at your own manuscript, where are the things where it doesn't. The things that you don't like, the things that make you go: ugh that is the third time that one word in this paragraph and not for comic effect, or: wait, have we heard that that's the case? is this a good time for that reveal or is it catching us off guard in a bad way? or...dozens of other things. Larger things too, things that are more particular to you, revelations you wanted the reader to have that didn't come through, elements that you wanted to include that fizzled and need to come out. Ways that the thing you wanted to write and the thing that you wrote have not lined up. Ways that you have changed your plan since you started and the traces of the old plan are still there. Ways that you have learned to see what is good and this is not it yet.
You can make lists if you want, if you feel like that will help. Other people have certainly made them for you, around the internet, things that are good to look for in a manuscript. If you like particular elements--if those are things you want to do--but you only notice them about stuff you've read later, in conversation when a friend points them out, those might be good to check for on a conscious level rather than expecting to notice them in your own work as you read. But they also might be good to just...have a friend who notices those things read for. It's totally okay to have someone else flag things in a revision for you. You don't have to be good at finding everything to revise yourself.
You also don't have to do everything a friend flags for you. Right now I'm having a long, involved conversation with a friend about their manuscript, and the result may well be that they leave the major element we're talking about exactly as-is. They may do acres of rewriting. I don't know. I don't even have to know. Because being a first reader, beta reader, even a sensitivity reader, whatever terminology you use...it's not about my ego, it's not about seeing my vision realized, it's about helping my friend with their revisions in their project. Which is, we have both noticed, not my project.
So: how do I know when I'm done? When I've done the stuff that needs doing. That sounds circular, but for me, setting a limit on each round is a good thing. You can always find something more to change--always. Ideally you will keep growing as a person and as a writer. The goal is not to be perpetually revising the same manuscript for the next fifty years. The goal is to make this manuscript as good as you can make it right now, for some value of now.
So for me, I do multiple rounds of "right now." I write the thing, I let it sit a minute. Then I read it through and revise it into coherence and send it off to first reader(s). Then I think about what they said and do those revisions. Then I either send it to editors if it's short or to my agent if it's long.
For long pieces, my agent has revisions, and we talk those through and think about them and I do them, sometimes in multiple drafts, until it's ready to go out. And then we rejoin the same stream as with short pieces: editors have it, they ideally want to publish it, they ask for revisions, I revise it, it gets published, I see all the things my current self could do better.
But I cannot do them better. Because "published" and "public" are from the same place. Published means that it is no longer mine, it is also partly yours. Published means that I am still responsible for the work but free of the burden of improvement. Published means that anything that is wrong with it aside from the part on page 7 where the protagonist's name is misspelled is going to stay wrong with it, and I might say, "I would not do it that way now, I don't think that now," but that is what that story says, even if it is not what I say, now, today. I do not say "Dramma," either, I say, "Grandma," even though 40 years ago I was saying "Dramma." People keep growing. You have to let yourself keep growing. You have to say, yes, that is what I said then, I did the best I could with what I had then, now I am doing something different.
Revision is a writer's best friend. It allows us to be better than our first impulse, and yet to retain that first impulse when it's the best thing available. But like any best friend, it's a better friendship when there are clear boundaries. That doesn't have to be my particular process. It may end up with several through passes I haven't listed for the sake of streamlining, in my own case--"I revise it into coherence" may mean "I have to read it through again to make sure that x element got woven through and then again for this or that other thing." The first chapter is going to get rewritten at least twice, I guarantee it, not because I feel like that ought to happen, but because it always seems to need it. But the question can never be "if I read through it again, would I find commas to rearrange," because the answer will be yes, you will, you always will. And when you're at the point of rearranging the deck chairs, er, the commas, onward, onward, go write something else.
