Just as writing children’s books has a unique set of rules to follow (you know that the good guy or gal always wins), there are some things you should never do — never! Don’t even consider doing any of the following in a book for children:
Write books that preach or lecture.
Talk down to children as if they're small, idiotic adults.
Write books that have no real story (nor a plot with beginning, middle, end).
Use art that is totally inappropriate for the story or vice versa.
Pack picture books with lots of text.
Pack nonfiction books with too much text and too few visuals.
Create characters who are boring or unnecessary to the development of the story.
Create main characters who have a problem they don't solve themselves or who don't change throughout the course of the story.
Tell instead of showing by using narrative as a soapbox.
Anthropomorphize animals or use alliterative names (Squishy Squirrel, Morty Mole — Wretched Writer).