@franky1: Your breakdown of the publishing paths is gold – especially the nuance between self-printing and being signed under a label. I keep reading horror stories of “vanity publishers” who basically sell hope, not books. But the idea that real publishers should invest first if they believe in a work? Yes. And that stipend concept? Totally forgot that was even a thing. Makes me wonder: what would be enough for you to say yes to a deal – full rights, partial rights, creative freedom?
full rights are ideal if you think your story is possibly good enough to maybe become a movie, because you get money from movie deal. where as partial rights is more so just like a royalty on the book deal but they own the rights to any other things like movies, audio books and such. so its upto you to think about the future of your story. is it just a novelty book thing or an intriguing story that has enough action/suspense that it can entertain movie watchers
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as for other idea's for developing your story, look locally for book clubs/readers clubs. get people whom you dont know nor related to, to read your book and get some real critique. also use them as a thinktank of experts if the book is unfinished, ask them where they see the direction of the book going, eg further character development or how they'd want the story to end
usually book club people have already read dozens of books of your genre so they'd know what works or not, and whats been repeated too many times in other books, that its become boring.. so ask them genuine questions like 'what would be an un-expectant plot twist or ending to make your book be better than others like it'
even with creative freedom, dont fear asking for feedback. you can always just not include it after they tell you. so no harm in asking