11 Dec 2015, 04:57

Way back when I studied 3D animation I used to frequent the forums on cgtalk.com. It's where I became a fan of Bobby Chu. It's not really for childrens book illustration IMO but you may find it interesting. (More video games and movies) I've used Deviant in the past still have an account but don't use it much.

You might also try the SCBWI forums as well. A few years ago I used to post illustrations there for feed back. You just need to be a member.