In every story your reader wants to know what, why, when, where, and how. They want to know how things look, sound, smell, taste, and feel.
Every story includes three ingredients: character, conflict, and resolution.
Start with a memory and then use your imagination to fill in the story.
Make sure your opening sentence grabs your reader right away to hold their attention to keep reading. Try a few beginning sentences - one will likely stand out over the others. That will be the path to follow.
Remember the hook, something that grabs your reader enough to keep them interested so that they keep reading. Over the years I have read many books that just didn't grab me and although I tried several times to continue, I eventually put the book away.
A lot of authors, I think in particular for children's books, end each chapter with a mini-hook that pushes you to the next chapter and the next. The chapter sometimes ends with a question that you may or may not have had but it sparks your interest, again, to keep reading.
The point is, always, to keep your reader engaged throughout the entire novel. And if you do, you just might have a bestseller!