It is important to have a general set of rules that I can enforce at any given time.
Some rules I would enforce is to respect ourselves and others, keep the classroom noise at a reasonable level, and ask if you have questions. Some specific rules for my classroom would be to clean up after yourself, use the art tools respectfully, and don't mess with other people's projects.
My daily setup for class would be to have a project ready for them to start as they enter the classroom, I would demonstrate the project that I am giving them and explain what they need to do for that specific project, and I wold then allow them to grab their materials and get to work on their project. At the end of the class period, they will have 5-10 minutes for clean up.