I kept it simple. I kept them in a circle on the carpet and only gave them one marker to use. Once we build our stamina a bit then I will allow them to choose spots around the room and use other materials to draw and write.
We are working on sharing after we are done writing. Some of the kids are really good at this and others are still unsure how to share their work. As each child shares I am modeling how to point out specific aspects in their pieces and draw everyone's attention to the things that "good writers" do.