Oh, that's a tough one. Cats love to play with tinsel and ornaments, and they can easily knock over a tree if they're not careful. One trick I've found to work is to put a sheet or blanket over the tree when you're not there to watch it. That way, the cat won't be able to climb on it or knock it over. And if you can, try to hang the most tempting ornaments higher up, out of reach.