[header] How to write best selling children's books [title] Pick an age range. [step] You do not want to walk up to an agent or publisher with a vague idea of your target audience. Agents and editors don't take well to book's that are " for all ages. 
" if you want to write a bestseller, it's important to have a niche age range in mind. [substeps] Things like picture books and stories with only a few words are usually for ages 2 to 6.