Attending critique groups and an occasional conference (expensive!) reading the current market guides and stacks of children's books and magazines is necessary---but you'll need to do more to stay up to date with this changing market.
One of the best ways I know to stay in the loop is to read The Children's Writer, a newsletter of writing and publishing trends. It's a MUST for me. This fabulous publication will tell you what editors want and don't want. You'll get tips on writing style in every area of children's literature. If you want a real challenge, try entering one of their writing contests. It's always fun to read the winning pieces. Who knows---one of those could be yours!
The Children's Writer did NOT ask me to write this. I'm just their number ONE fan. I'm thinking about getting a baseball cap with C.W on the front. Hmmm...on second thought, a book bag would be more my style. Anyway, go to their website. They're offering a FREE trial issue!