I have copied and pasted something I have recently read, about first drafts of a novel. It's here:
First, congratulations on finishing a first draft! Not many folks get that far.
Now: Go through the entire book and write it again.
I don’t care if you’re a super-genius who makes Tony Stark look like a complete numpty, if you have a first draft you’re so far away from publishing that publishing is a distant speck waaaaaay off in the horizon.
Write it again. Polish every single sentence.
When you’re finished, write it again.
Nobody’s first draft is a final work. If you’re a skilled, experienced writer with many popular published novels under your belt, you might have something that’s ready to show someone else by your third draft, maybe.
If you’re talented and lucky.
More likely, you’ll need 5–6 drafts. And that fifth draft will probably look quite different from the first. This is how it works.
So go through the entire book and write it again. And again. And again. And again. Make every word shine. Make every sentence sparkle. Check and re-check and re-re-check for continuity. Be willing to delete parts you really really like, if they don’t serve the story. Be willing to rewrite even when you really really don’t want to, if there’s a bit that isn’t working.
Once you’re done with your fifth or perhaps sixth draft, find a substantive editor and pay them. Get feedback from people you trust—and I don’t mean your parents, I mean people willing to tell you “This bit is crap.
I thought it was interesting, but I 'm not sure I would ever get to five or six drafts.