Don’t take writing advice until you’ve written a book.
It seems counter-intuitive, I know, but I just recently watched an ad promoting a writing course. I generally dislike such programs, but that’s just me. But then it stipulated ‘even if you’ve never written before’.
If you haven’t finished the book, don’t take the writing course. Don’t take a writing course, don’t join a writer’s circle, don’t sign up for a writing class. Do one thing and one thing only: finish the book.
When I say ‘finish’, I don’t mean polish and make ready for publication. I don’t even mean edit it. But I do mean write out all the scenes and sequences.
You cannot improve a book that doesn’t exist. You can’t improve a story that is still just a concept and not a tangible work. Once you have a completed manuscript, you can edit it. You can improve it. You can hand it off to others and ask ‘how can I make this better’. You can take the raw materials of your rough draft through the lessons of that writing course and address all the needs. But taking the writing course before the manuscript is done, before the book is completed, is putting the cart before the horse.
Put pen to paper (proverbially or literally) and finish the book. Everything else waits until the book is done.
Don’t worry about the quality, don’t worry about plot holes or characterization issues or tone or any of that. You worry about that in the editing phase, you worry about that in the review phase. Until the book is done, you have one job: write. Write and finish the book.