Keep the base of your tree in plenty of water. Select the location for your Christmas tree carefully, keeping it away from fireplaces, heating vents, and other heat-producing appliances that may dry out the tree. Before the tree dries out and starts dropping needles, move it outside. Never try to burn branches from the tree in your fireplace. Most light sets are made properly, but too many are not.
Fires caused by short circuits in holiday light sets are far too common.
Check the strings for signs of wear and tear. Do not use lights that are frayed or operate with missing or broken bulbs. If the plug or wires feel warm at any time, throw them out. Use no more than three sets of lights per extension cord, and do not place the cords under rugs or in paths of travel. And never use indoor holiday lights outside.