Determine if you actually need an agent. Unlike publishing houses that cater to the adult market and refrain from reviewing submissions sent by anyone other than a reputable literary agent, children's publishing houses sometimes will interact directly with authors.
Verify if the publisher you're interested in working with accepts unsolicited manuscripts directly from authors by studying its website, asking other authors you know or consulting either the "Children's Writer's and Illustrator's Market" or the Children's Book Council's online membership list.
Obtain a copy of "Literary Market Place" at your local library or bookstore to identify agents of interest if you confirm that you do need an agent. Other trustworthy sources include "Children's Writer's and Illustrator's Market" and the online database at Agent Query.
Ask editors, fellow writers and published authors you know to recommend any agents they think would be interested in the type of fiction you write. Writers who have already forged a successful relationship with their own agent can provide invaluable insider information on how to pursue the same for yourself.
Compile a list of potential agents from steps 2 and 3, making sure that each handles your style and age level of writing. The details should include as much contact information as possible, such as specific names and titles, addresses, telephone numbers and websites.
Visit the website of each potential agent to confirm that he or she is legitimate and capable of properly marketing your children's fiction manuscript to publishers. Things to look for include a complete list of clients, where and what those clients have published, a clear overview of the agent's qualifications (for example, length of time in business, specialization, and industry experience), submission guidelines and contract terms for clients (for example, the amount of money required for commission payments and expenses).
Don't become discouraged if all of this information is not available in one place. As long as most of it is, you can fill in any holes with secondary references, such as acquaintances, telephone inquiries and source books.
Verify if the agents you are most interested are members of the Association of Authors' Representatives, an organization for independent literary and dramatic agents. Membership is not an industry requirement, but it will indicate that an agent is bound by the association's code of ethics.
Confirm that any agents you are interested have not received bad reviews on Predators and Editors, a website that compiles reports of fraud and other complaints against agents.
Compose a brief letter of no more than three concise paragraphs to each agent of your choice explaining what your book is about and your background, if it is relevant to your viability as an author. Use postal mail, not email, and make sure to also include an SASE (self-addressed stamped envelope) for a reply.