Sol Stein is a well-known author and editor and his take in this book is all about structure and editing.
He gives clear examples of how to craft your work, review it and edit it. I found it a little dated with references to what is expected in the 20th century but that is when it was written and it doesn’t take away any of the good examples of what not to do or how to redraft your work.
It is very much about editing and restructuring but it is worth having just for that.
Don’t get too bogged down in this before you have your first draft on paper but reading it before writing might help you to avoid common mistakes as you go along so that you have less to do afterwards.