The best way to string Christmas lights on a tree is to start at the top and work your way down. First, make sure that your lights are in working order and that you have enough of them to cover the entire tree. Then, wrap the lights around the trunk of the tree, starting at the top and working your way down in a zigzag pattern. This will ensure that the lights are evenly distributed and don't overlap too much. Once you reach the bottom, plug the lights in and admire your handiwork!