If you are on a serious mission to get your book published but are having absolutely no luck, there could be an option worth considering. The problem is you may not want to consider it.
So here it is; a possible course of action if all else is failing: start again.
It’s brutal; your masterpiece is like a baby to you and now I’m telling you to press delete; this seems like one step away from giving up altogether, but stick with me; I’m about to make sense.
As a serious writer, which you probably are if you are reading this, you will be used to editing everything you write, possibly getting through several drafts before feeling even remotely satisfied with what you have written. All I’m asking you to do is to take it one step further and do the ultimate edit; start the whole book again.
Assuming the plot is not the problem; you feel you have a great story and don’t want to change the basic premise; then starting again will open up a new direction for your story to flow in. You will almost certainly find that your new literary construction will build differently to the first and you will be amazed how little changes in direction will lead to some substantial changes in the storytelling. Even if your plot stays the same, which often it won’t, you will find yourself merging old ideas with new, rethinking the story and coming in from a fresh angle. Yes, it is hard to start again from the very first word, particularly if you have been a slave to your keyboard to reach a satisfactory final chapter, but often the process absorbs us so completely that we tend to focus too much on every tiny detail rather than concentrating on writing the entire story. Try to remember that getting it done is better than getting it perfect; there is time for that in the edit.
Starting again will not be an easy decision, but if it is likely the case that there are some fundamental flaws in your first draft then it makes a lot of sense, and could lead to an ironing out of faults you were not even aware of. Many a good author has found contradictions and mistakes in stories which appeared at first glance to be accurate, so it stands to reason that you, a novice, will make similar mistakes. Writing may come as naturally as breathing to you, but you are still going to make errors in grammar, detail or fact, and these will be picked up like a chicken in a foxhole by any discerning reader.
Depending on how you feel about showing your unfinished work to people, it is always a good idea to enlist someone you trust to look over what you have written; however, this can only work if your chosen person agrees to be absolutely brutally honest and constructive. If you choose someone who will want to spare your feelings then they are not the person to give an honest assessment, so be careful with this course of action. You can always hire someone to read it through; it doesn’t always have to be expensive, just check out Fiverr for any basic book-related services
Starting over again is never going to be an easy decision, but if you can look at the bigger picture and realise that for the sake of a few months rewriting, you could have a substantially improved product that will stand a better chance to become a big seller.