I love writing tales for children. There is a moment when an imagination arises and you just start writing, like the lovely flow of a creek, winding here and there discovering more ideas as we give in to the flow. This comes from our inner most spaces, and we learn to trust it.
At the heart of writing stories for children is the act of conscious walking in nature. When we form a rhythmic walking with our hearts, eyes, and sense of wonder open, something wonderful happens. The left/right orientation and movement of our bodies when walking balances us, and our brain is engaging in a more creative way. 
We walk in the beauty quietly, our inner lives listening and looking. When we do this our senses are more open and we notice things differently. Our imaginations expand and breathe. This is when nature's muse will begin to speak to you and through you. Notice.
What did you discover in this activity. This is the foundation of opening up our imaginations for story idea gathering. What time of day is it? What is the natural setting like? Ocean, forest, meadow etc.? How did your body feel? What is one thing you noticed ? There are no right or wrong answers - this is your experience.