If you write for a younger audience, at any level, than JOIN THIS GROUP. It was the best writing decision I've made so far.

scbwi.org

Yes, the acronym is as clunky as they come, but I've heard the story behind its existence (it's not that funny, but I know it!)

The group includes writers and illustrators of Picture Books, Early Chapter Books, Middle-Grade Novels, Young Adult Novels, Hardcore Teen Novels, Nonfiction magazine articles and books, graphic novels, and way more.

Everyone is welcome and is welcoming, at all ability levels, from rookies to pros. That is not the case with many other writing organizations. Instant market updates. Easy to find In-person and online critique groups. My local MI chapter is super active. The conferences I've attended have been first class with easy access to writers and editors. You get a huge foot in the door by being an SCBWI member. It really is worth it.