DO water daily with clean fresh water – trees use an average of 1 qt. of water per inch of stem diameter. First week you'll see your tree drink quite a bit of water. Water temperature and additives have not proven any more effective in preserving your tree.
DO protect your tree from direct heat sources (fireplaces, heat vents, heaters, & direct sunlight) these will cause them to lose moisture and drop their needles at a much higher rate.
DO trim off 1/4" the bottom IF it has been more than 5-7 days since it was harvested. If you place your tree in water within 12 hours of cutting, you do not have to trim off the bottom.
DO place in water and keep in a cool place if you are storing your tree for a few days before use.
DO run your fingers across the needles to monitor if they are dry and brittle. If the needles break easily or fall off in your hand, the tree is dry and should be remove from the house.