The best way to clean a Christmas tree is to first remove all of the decorations. Then, using a soft cloth or a feather duster, gently wipe down the branches to remove any dust or debris. You can also use a vacuum with a soft brush attachment to suck up any loose debris. If your tree has lights, be sure to unplug them before you begin cleaning. Finally, make sure to give your tree a good watering before you decorate it again!