Determine which youth book publishers to target for submission. The best way to do this is to find niche publishers that your book fits well with. For example, if your story covers a particular religion, you may want to target publishes that specialize in the youth market for that religion. This will narrow your number of submissions.
Call each book publisher directly or visit their website to find out the publishers submission requirements and guidelines. Requirements will vary according to editor preferences for each publisher, so a one-size fits all approach will not apply. You need to get detailed submission guidelines for each publisher before preparing final manuscripts.
Prepare a separate manuscript for each publisher you will submit to. Make sure you adhere to the submission guidelines and editor requirements in your manuscript. If you do not, your manuscript will likely end up rejected.
Send your manuscript to the publishers, following all required submission guidelines. If the publishers likes your book, the publisher will contact you to discuss a contract before editing and going to press.