To fluff an artificial Christmas tree, start by using your hands to gently separate the branches and fluff them out. If the branches are too stiff to move, you can use a wire brush or a soft-bristled brush to help loosen the branches. Once you have the branches separated, you can also use a hair dryer on low heat to fluff up the branches even more. Make sure to use caution when using a hair dryer near a tree with lights or decorations, as the heat from the dryer can damage them.