I HATE BEING OUT!!!!!!!!!!!!!!!! But when I am...I make sure that my sub has EVERYTHING they need for success in my art room. I lay out all the supplies, paper, instructions, books....whatever so that they do not have to hunt around. You may think your supplies are easy to find(or that your kids can help them out), but they might not. So why mess around...lay it all out!
I set up the still life that I left for 2nd grade...and even put a sign on the side..THIS IS A STILL LIFE..MOVE IT TO THE CENTER OF THE ROOM FOR THEM TO DRAW THE ITEMS "ON" THE CART..NOT THE CART ITSELF.
I put rags out with a note...telling them which classes truly needed wet rags to clean up with.
I do have an emergency box for those times I don't know I'm going to be out(though this has not happened). We have to have sub folders in the office...and in mine it tells them where to locate the box.