Read 200-400 page standalone novels. Don’t start off with series, as character development is usually a larger arc and there’s potential for a lot of characters.

Also really hone in on the genre you’re looking for in fiction, as well as the plot. Is romance your thing? Science? Swords and shit? I recently read the Martian and I loved it - way more science based than a fiction I’m used to, and no romance so pretty good for nonfiction readers.