The best way to hang garland on a Christmas tree is to start at the top of the tree and work your way down. Begin by attaching the top of the garland to the top of the tree with small hooks or pins. Then, wrap the garland around the tree in a spiral pattern, making sure to overlap each layer slightly to create a full and festive look. Once you've reached the bottom of the tree, secure the bottom of the garland with a few more hooks or pins, and trim off any excess if needed.