Start by peeling off the silver "Boo" and any other silver sections from the hat. These could show through the burlap, but the black won't.
Flip the wreath over and use scissors to cut off the extra ends of the hat. You won't need those, and they can make the hat stick out to the sides.
Lay out the bushels of fall leaves to decide how you want them to be seen. Group them into sections of 2 and zip tie them to the backside of the hat. Ensure that the leaves are below the hat, giving it a layered look resembling a gnome's beard. Trim the ends of the zip ties.
Lay a piece of burlap under the hat and trim around it to avoid excess. Add hot glue to the plastic sections on the backside of the wreath and fold the burlap over it. Press down firmly to attach it securely.
Repeat this process until the entire hat is covered. You can fold over the end of the burlap to create a lip, allowing you to add the orange mum flower and one of the berry picks.
Add a dab of hot glue to the backside of the ping pong ball and press it firmly onto the leaves.