To fluff a fake Christmas tree, first start by gently pulling the branches outward to separate them from each other. Then, using your hands or a soft-bristled brush, gently fluff the branches, working from the bottom to the top. Be careful not to overdo it, as too much fluffing can cause the branches to break or become damaged. Finally, use a comb or brush to smooth out any rough edges or creases, and you're done!