Here’s an article on choosing books that might help get you started.
You can always give it a one-page test: Flip it open to a page and start reading. If it pulls you in and makes you want to keep reading, it’s probably a living book. If you get to the end of the page and think, “OK, whatever,” it’s probably not a living book.
As the article mentions, the more practice you have with living books, the easier it will be to spot them. So hang in there!