When you are writing for children you should begin with a specific age group in mind. The writing style for a picture book is vastly different from that of a young-adult novel. It is important that you choose specifically what age group you want to write for when you begin to plot your story. To figure out the style and tone to take, read books written for that age group. If you want to write picture books, read several. This will help you understand the rhythm, tone and style.
The most common advice agents and editors give is to make sure that your main character solves his own problems. If the parent or another authority figures sweeps in and fixes everything, the story will not be as effective and young readers will be disappointed. You can have parents offer advice, but ultimately the main character must take care of the problem. This applies from picture books up to young-adult literature. The problem does not necessarily need to be solved, but there should be resolution and the character should grow and change as a result of the problem-solving.
The key to good writing is taking the time to revise your work. Keep things as clean and simple as possible. Good children's stories follow a plot that moves quickly. As you revise, cut out unnecessary scenes, words and actions. Read the story to children. Watch where they lose interest, then work to fix those sections. Join a critique group and get help from other writers. Revision is more than fixing punctuation and grammar mistakes: It is looking at everything from plot structure to character development. Read the book out loud to catch mistakes and to listen to the rhythm of your story. Once you have done this, have someone else read over the manuscript to catch errors you may have missed.