Answer:
Ray is most likely recommending that Walter learns more about trends in the publishing industry. Since Ray mentions the business side of writing, understanding trends in the publishing industry would be valuable knowledge for Walter. This knowledge would help Walter navigate the ever-changing landscape of the publishing world, including emerging genres, popular writing styles, market demands, and reader preferences. By staying informed about trends in the publishing industry, Walter can make more informed decisions about his writing and potentially increase his chances of success in the competitive market.