If you plan to buy a cut Christmas tree at a garden center or a tree lot this year, there's no need to wait to buy it, even if you don't want to put it up yet.
Because the trees are already cut, they will not be getting any fresher. So bring the tree home and put it in a bucket of water on the north side of the house. When you're ready to bring it in and decorate it, cut an inch off the trunk and immediately put the tree in water in the tree stand. Never let it be out of water after this point.
Here's how to select a fresh tree: Gently hold a branch between your thumb and forefinger and pull it toward you. Very few needles should come off in your hand if the tree is fresh. Or shake or bounce the tree on its stump. You should not see a lot of green needles fall to the ground, though interior brown ones probably will.
When you bring a tree into the house, put it in as cool a spot as possible. Avoid areas near fireplaces, wood-burning stoves, heat ducts and television sets.
Make sure the tree stand's reservoir stays filled with water. If it ever does lose enough water that the bottom of the trunk is exposed, the trunk will need to be recut. Adding aspirins, copper pennies, soda pop, sugar and bleach to the water have not been shown to prolong the life of a tree.