@Myastry_magic I just thought the idea was pretty interesting as some stories have played with ideas of possession before, but never quite fully explore it so I took the idea and ran with it.
As far as writing goes, it's honestly hard to quantify what counts as good advice, as it heavily depends on what kind of genre you write. But honestly, if you are willing to put in the work, continuous, consistent, and regular practice at writing will bound to get you closer to figuring that part out. There are also free college level courses online that I do watch sometimes if you need more "professional" guidance (like Brandon Sanderson).