If you havent read these yet I really recommend Slouching Toward Bethlehem by Joan Didion (pdf available online) a map to the door of no return by dionne brand (some good poetic base in there as well), and this article that goes over some basic ideas https://brevity.wordpress.com/2021/08/13/good-cnf/#:~:text=Good%20creative%20nonfiction%20writing%20is,%2C%20or%20purpose%2Fcentral%20idea.