Random! I have notes everywhere...in notebooks, on post-its and in my phone but when I sit down to write I get hyper focused and will lose track of all time and reality. I also usually have my cat on my shoulder because he insists!
When my youngest son was learning to read, he didn't like the books being sent home for him to practice with which made it homework difficult for the both of us. So I self-published some easy readers about him and his dogs; he loved it and would read to anyone who would listen...including the dogs. Since then, my books have still followed his reading levels and interests, it's like my books are growing up with him.