1. Join the international Society of Children’s Book Writers & Illustrators(SCBWI): https://www.scbwi.org/. There is no better organization for writers of children books. If your state or country has a local chapter, one membership should cover both. Take part in their conferences and workshops. Not only will you improve your writing skills, but you will make connections and friends.
2. Check out this article: SCBWI | Frequently Asked Questions.
3. Join Writer’s Digest: http://www.writersdigest.com/. Although they are focused on writing for the adult market, they also have valuable articles and webinars specifically geared to writing for children.
4. Join or start a children’s book writers critique group. Your local SCBWI chapter can help you find a group near you or help you form a new group.
5. Know your genres. Are you writing picture books (PB), early readers (ER), middle-grade (MG), or young adult (YA)?
6. Read books in your genre. Lots and lots of books. Know what’s contemporary as well as what’s classic.
7. Love your genre. Don’t write in a genre that doesn’t get your passion and creativity flowing.
8. If you can afford it, hire a book coach or an editor. Writer’s Digest offers a service called Second Draft. I have used it, and the editors are excellent and respectful. Outside of that venue, do your research. Be sure the person you hire is credible and has references. Check the references.
9. Give yourself time. Don’t rush the project out to agents or publishers. Revise. Revise. Revise. There are no second chances for making a good first impression.
10. Never give up.