One way to decide what to read next is to let the current book you’re reading be your guide. In a blog post Austin Kleon described the idea of books being either centripetal or centrifugal, in other words some books suck in you and some spin you out. Some books will frequently be referenced by other books and they are ones you’ll return to again and again, they exert a centripetal force. Other books will generate lists of new books to seek out sending you outwards—a centrifugal force. This is not an objective measure, what is centripetal for person maybe centrifugal for another.
In Jenny Erpenbeck’s book Not a Novel: A Memoir in Pieces there are two chapters pushing me outwards towards my next potential reads. One chapter is about Ovid’s Metamorphosis and the other about Thomas Mann in which Doctor Faustus is mentioned among his other writing. Both of these books I have and I’m strongly tempted too follow this thread from Not a Novel, outward to one of these other books—perhaps starting with Ovid first and then Mann.