Reading in your genre
Genre readers have expectations built up over hundreds of books. They know what a fantasy magic system should do, how a romance should structure its emotional arc, where a thriller should place its reversals. You can break those rules, but the break only lands if you understood the rule first. Read widely in your genre, especially the books your readers cite as their all-time favourites. Those books are your competition and your curriculum. If you cannot identify what they do that you do not, you are missing the most accessible improvement available to you.