There are four main categories for kid books: 1. Picture books 2. Chapter books (Tree House Series) 3. MG or Middle Grade Novel (Ages: 9~12 app) 4. YA or Young Adult (12~18 app).
Before you do anything, you must write the book-the whole book from beginning to end. This is called a completed manuscript. Agents and editors want to know if you can finish the job.
After you have congratulated yourself for actually finishing a novel, you should celebrate and then put the thing on a shelf for a month and not look at it.
A month later, look at the manuscript and fix it. You will see problems that were not there the night you were celebrating. This is called editing. For many, this is where the real work begins.
When you have finished this revision, you need to give the manuscript to some readers. Choose people who actually have the time to read and know something about grammar. Most importantly, get someone to tell you the truth. You will need to thicken your skin. Criticism lines both sides of the road to publication.
Once you have polished the manuscript to shiny silver or gold, then you need to find an agent. An agent not only will open doors for you but she will get a better deal for you. Where to find an agent?
Join the SCBWI. The Society of Children's Book Writers and Illustrators. The SCBWI is most fun group of people on the planet. They have the best parties, I mean, conferences, where you laugh and learn a lot.
Next step: Go to a conference. One, you will meet other people who are crazy enough to be writers. Two, you will go to break out sessions and learn the nuts and bolts of the business. Unfortunately, conferences are expensive.
It is at the conference that you will meet agents and editors.
After the conference, you will write a query letter, telling the agent about your project and (hopefully) sending in a few sample chapters.
Most queries end in rejection. This is called a part of writing. It's a sad but true fact of the business. Fewer than 1% are taken. Most agents receive several hundred queries a week; most sign only a few new authors a year. The math in the writing business is bad, but the best thing going for you is that editors need new material to publish every year. The reality is that there is mucho competition in the market, so editors can be choosy. Make your work the best that it can be BEFORE you send it out.
If the agent takes on your manuscript, he will send it to an editor for whom he thinks the project is the best fit. Sometimes, this is known as getting the best price for your work.
If the editor likes it, she will try to "sell" the book in-house. This means that even if an editor likes the book, she needs her publishing house behind the project. She wants the marketing guys who talk to Barnes and Noble to get behind the book or the book may not get a good spot on the shelf. And if that doesn't happen....
If everybody is on board, the publishing house will send the agent an offer to buy the manuscript. The offer might include an advance, royalties, and a whole bunch of other gobblygoop that makes you happy you have an agent to figure it out. Then you agree on the details and sign a contract.
Then the author and the editor go to work on making the book the best it can be. This is the time to throw the remaining parts of your ego out the window. Smart new authors do pretty much everything an editor tells him to do. The project moves to copyediting, where a person with very good eyesight fixes the typos and grammar and other mistakes you have overlooked. The publisher designs the book and prepares to market it. This process of getting a manuscript to the bookstore can take a year or more.
Lastly, the book sells like mad and you're filthy rich. Haha. Prepare to devote time, effort, and money to hitting the pavement and selling/marketing your book.
Publishing is very hard. That is why writers write, editors edit, and publishers publish. Now, go and write the best book you can.