What Should Authors Look for in Children's Book Publishing Services?

I've recently finished a manuscript for a children's story and started exploring children's book publishing services, but I'm feeling unsure about what really matters when choosing one. Some services focus on illustrations, while others offer editing, marketing, and distribution support. Since this is my first time publishing in this genre, I want to avoid common mistakes. For authors here, what features or support in children's book publishing services make the biggest difference for your book?