The best way of doing that is to write a book that you would have enjoyed when you were young. And the best way of doing THAT is to write for the child that still lurks inside you. Then forget it. Based in the UK, Michael Coleman is the award-winning author of a number of books for children and young adults. It is my opinion that art inspires art.
Life inspires art.
Thus, one must live to the fullest and experience beauty with all of his senses in order to create. The children's author must live by the same pursuits. Gather inspiration where you find it. Share your endeavor with a writers' workshop. Perfect the piece.