Good one, Cheri; I remember seeing this or something like this many times before and it's amazing how fast that fire starts, isn't it? A lot of folks think, "Oh, that happened mostly when Christmas tree light bulbs were the really big ones and started the fires so we are safe with the mini-lights." Well, I don't think so; even with mini-lights, you can have a short in the wiring so check your wiring very closely every year before stringing them on the tree; look for cracks in the plastic covering the wire, etc. Check the brand new lights you buy for defects and then every year thereafter. If you begin to notice aging of the wiring in places, trash it. It doesn't cost that much to replace compared to what might happen.
And, oh yes, what Cheri said about watering the tree. Don't keep the tree too long because, even with watering, the tree will eventually dry up.
Have a safe holidays!