We see a lot of wonderful preteen books from self-publishers. Besides a great story, there's something else they need to attract the eyes of young readers. Preteen books need to be formatted in a kid friendly way. What does this mean?
Many of these self-published books are formatted by the authors, probably using Word or WordPerfect. Unfortunately, the text is small, the chapter headings boring, and page headers are either dull or non-existent. Now, this is fine for books meant for an adult audience. But youngsters need some encouragement to pick up that book. Consider using a larger size font (looks less intimidating to reluctant readers). Dress up your chapter headings. For example, my preteen horse books have a small horse jumping through/around the chapter number. Page headers are great too as they help kids find the chapter they're currently reading when it's time to resume reading. Take a look at other chapter books to see what your competitors do. Your young readers will be glad you did!