|In real life, Alessandra Balzer isn't this blurry.|
One of the first things, of course, is voice. Even with picture books, it's a critical way of understanding characters without lots of exposition. (Some favorites: Bob Shea's I'M A SHARK, Mo Willems' Pigeon books, and SKIPPYJON JONES.)
You also need a groundbreaking concept. What does the market need that it never knew it needed? She gave a couple of examples, including the picture book JUST BEING AUDREY. Something that isn't out there, or something that gives a fresh take on other stuff.
Thing three for Alessandra is world building. It doesn't have to be sci fi or dystopian--it could just be a really believable high school, created from the atmosphere to the dialogue and clothing. How is speech different? How are social moires different? If you don't figure all that stuff out, it won't work.
Read-aloud quality. This doesn't stop with picture books. She recommends reading your text out loud to yourself. "It really changes things when you hear your own voice doing it," she said. The book CAT SECRETS blends humor with sound effects--the reader is forced to interact.
Heart. This is the X-factor that crosses every genre. "It's the thing that makes you go awww. It's the emotional resonance. It's the thing that makes you want to root for a character."