The best way to make a Christmas tree look taller is to use a tall and narrow tree. The taller the tree, the taller it will look. Additionally, you can use ornaments that are hung high up on the tree to help give it a taller appearance. You can also use a ladder or step stool to reach the top of the tree and place ornaments there. Finally, you can use lights or garlands that drape down the tree to add a sense of height and length.