The first things to get out of the way are the obvious pieces of advice. These are reiterated across dozens of forums and blogs: know your target demographic, narrow down your book category, and know the children's book market. Though this might feel like three separate pieces of advice, they all boil down to one idea: follow the format.
Writers love to break rules, make mistakes, and push boundaries. Writers also want their work to be seen, and they want to make a living with their writing: that means getting published. To have a realistic chance of being published, a children's book needs to meet the expectations of the publisher. There are three primary reasons publications have such seemingly strict requirements: logistical, traditional, and marketing requirements.
Logistical limitations: Know where you will publish
No matter your work, there are logistical limitations in publishing. If you want to produce a book of an unusual size – very small, or as large as a small child – then the number of publishing houses who can work with you is greatly reduced. Most publishing houses simply lack the equipment to make your dreams of a two-foot by three-foot storybook a reality, even if that is the big selling point of your work. The same is true of length: there are particular word counts for each product and age group which will – on average – increase profits for the publishing house. For the 3-7 age range, about 750 words seems to be the sweet spot with very few exceptions.
When a company prints many books, it benefits them to print books of a similar size and length – it streamlines the production process. If you ask a company to change their business plan to accommodate your needs as an author, you are less likely to get pushback than you are simple radio silence from their human resources department. Simply said, it may be best to determine possible publishers before you start writing, or get a general idea of the industry standards for children's books.
Traditional limitations: Breaking away from tradition
Don't feel constrained by the industry's expectations of your work, but do take them into account before you begin writing. If you are seeking traditional publishing, make every effort to adjust your work so that it fits the industry standards described above, without sacrificing the parts of your story that make it unique or appealing. If your publishing plan is more flexible then there are a number of self-publishing routes which may make sense for your work. Unfortunately, many of the costs in non-digital self-publishing are born by the author. For children's books especially it is often important to provide illustrations which are costly and require a professional; and for new authors it may not be feasible to pay up-front for large print runs necessary to produce economies of scale.
The solution is to take your time. Submit to traditional publishing houses first, and rely upon self-publishing next, and only after you have assessed the risks and your own budget. Don't close off opportunities due to your own bias: traditional publishing is not so restrictive as you might imagine, and self-publishing is not nearly so easy or profitable as some authors make it seem. Finally, beware of scams.
Marketing requirements: Niche and questionable content
It may seem basic, but it is important to ensure that your work doesn't have any glaring complications for publishers in terms of content. Children's stories should usually distance themselves from ideological claims, except where that ideological claim would be considered an obvious truth by the target audience. For instance, encouraging children to attend to their homework is much less controversial than encouraging children to learn how to fight or defend themselves. The first moral would be considered an obvious truth and the second would not, though arguably each skill is valuable.
It is also important to distinguish questionable content from niche content. What may be questionable in a general sense may be progressive within a certain community. A book promoting self-defense and self-discipline may find a target audience in certain martial arts classes or communities. It is an especially strong strategy, if you have niche or specialized knowledge, to use that knowledge to produce content that others cannot.
Equally valid is the attempt to make questionable content less questionable, or to expand a niche idea to a wider community. Progressive children's literature can be very marketable if you engage with an interest that is starting to become widely accepted, such as the idea that female children should be pursuing technical (STEM) learning. This is the marketing lever behind Andrea Beaty's Rosie Revere, Engineer. Less successful are works which engage with universally difficult subjects: suicide, religion, politics – basically anything you wouldn't bring up at a big family dinner. Still, these books can and do get published. If in doubt, ask yourself this question: is the content of my work impacting the appeal of my story?
Content vs. appeal
In writing, content is the take-away concept from a work, and appeal is the reason readers picked up the book in the first place. The appeal of Harry Potter, for instance, is the fantasy world described by J.K. Rowling in which wizards cast spells, and wherein dragons, elves, and flying cars add excitement to each school year. The content that leaves a lasting impression are the themes of loyalty, bravery, and friendship. When writing your work, it is important to balance each of these concepts, and to be aware that content and appeal are often at odds.
A series with a high amount of appeal will often be considered content-less. A good example of this is the R.L. Stine Goosebump books which teachers often denigrate for their lack of content and reliance on gross textual imagery and shocking cover illustrations. Still, there is no reason a work cannot have high appeal, and respectable content: most Dr. Seuss books are highly appealing to their target audience. His books use rhyming words and vibrant colors, but they also develop vocabulary which is age appropriate, and often teach a moral, such as the theme in Green Eggs and Ham, which is try something before you decide you don't like it.
In some cases, like when marketing to a niche community, either content or appeal will take precedence. Certainly, Rosie Revere, Engineer is often purchased for its content – it teaches little girls that they can work in stereotypically male-dominated positions, and books like Captain Underpants are bought for their appeal – kids like them. That being said, neither appeal nor content can be ignored. Captain Underpants is a series with high appeal, loved by kids, but also loved by any parent who is struggling to help their child become interested in books.
Parents vs. children
Many book blogs tell you to "discover your best idea" or "develop your main character," but they don't give a reason to do so other than a vague sense of authorial merit – and that may be a very real reason to ask these questions. A more cynical reason to choose your content carefully is that, mostly, you are writing for the parents of the children, rather than the children themselves.
As a rule of thumb, parents seek out content and children read books based on appeal. Of course, ignoring either appeal or content is a mistake, but often-times a book can get by with more of one than the other. The younger the reader, the more you should consider the parent, and the more important content becomes. Stories like I Love you to the Moon and Back, by Amelia Hepworth are purchased by parents, and are designed to appeal in terms of style and content, to parents. By contrast, as children grow older and make more of their own decisions regarding their reading choices, series with reoccurring characters and plenty of content seem popular: Rick Riordan's Percy Jackson series, the Animorphs from my childhood, or the currently quite popular Warrior Cats series. These are each in-line with Goosebumps in terms of their writing quality, and obviously favor appeal over content, usually eschewing dangerous/controversial subjects to retain their marketability.
Last word
As a writer, an editor, and an academic in the sphere of Young Adult literature, I have only one further piece of advice to offer writers of children's books, and of literature in general. In writing, there are very precise guidelines – word counts, page numbers, punctuation styles and other best-practices. All of these things can be ignored, but rarely should be. When you are choosing whether to go with the industry standard, or break a rule, ask yourself: is it necessary to break this rule, to tell the story that needs to be told, or am I simply breaking the rule because I have a general sense that it would be 'better' to do so? If you don't need to break the rule, or you can't define exactly why your way is 'better,' than always – always – lean towards keeping the rule intact and following the format. Exceptions to a rule are just that – exceptions.
