I highly recommend you join a group, like SCBWI, whose goal is to build a network between people in the industry.
I suggest you read, read, read. The more children's books you read, the better your intuition will be.
And I suggest you avail yourself of the experience of other writers and editors.
My favorite how-to for writing children's books is by Jean Karl. Her book, How to Write and Sell Children's Picture Books, has done more to shape my writing than any other book on the subject. She breaks down the categories within the field and gives pitfalls to avoid. Her keen editorial mind zeroes in on the essence of a good picture book. Best of all, Jean Karl is inspiring. She make writing and publication seem plausible. She makes the possibilities seem limitless. I never fail to read through her text without acquiring a half dozen new ideas.
So what are you waiting for? Grab a notebook and start writing. Then head to your nearest library (and bring a BIG bag.)