Polish your typewritten manuscript, ensuring it's at an optimum quality to submission. Join a children's writer's critique group for feedback or hire an independent children's book editor for a professional critique.
Decide if submitting to the publisher or an agent. Some children's book publishers have an open-door submissions policy including unagented manuscripts, whereas others require agent-only submissions. Submitting to an agent does not guarantee manuscript acceptance by the agent.
Research editors and publishers for the best possible fit for your manuscript. Consult Children's Writer's and Illustrator's Market, an annual publication with listings for publishing opportunities. Check library and children's book sections in the bookstores for editors publishing similar books as your manuscript. Join the Society of Children's Books Writers and Illustrators to attend industry seminars where guest editors detail project preferences and invite direct submissions.
Refine the query letter or book proposal and follow individual publisher guidelines. A query letter is the initial letter of inquiry for fiction and picture books, while a proposal is includes outlines for non-fiction manuscripts and novels. Some publishers accept complete manuscripts, while others prefer sample pages and still others request only the query letter.
Submit to multiple publishing houses whenever possible. While publishers request a courtesy notification of multiple submissions, other publishers require exclusive-only submissions. Under exclusive submission, the manuscript remains under review with one publisher, and may not be submitted elsewhere, until the publisher makes an offer or rejects the manuscript.
Review your book contract with an agent or lawyer to ensure your rights are protected.
Some writer's organizations such as The Author's Guild offers free legal review of book contracts for its member writers.