Select a good tree. If you are going to put your tree up early, avoid spruce trees. These trees dry out faster and will drop their needles quicker than other varieties.

If you are going to cut your own tree, you should know that if a tree is close to the woods it will have a side that is full that is facing the sun and a backside that is thin. Those trees will tend to tip over as well.

Be careful to select the proper size of tree. Don't overdo it, because when the trees are in the field they don't look as big as they will once they get in the house. We like to joke that the trees tend to grow as they go through the front door!

Pick the freshest tree you can find. Test the tree by grabbing the needles and gently pull them toward you. On a fresh tree, the needles will stay on the tree.

Don't be put off by a few brown needles. However, all trees have these. Have the business put the tree in a shaker, which will dislodge all of the dead and loose needles. It's an expensive piece of equipment, so not every Christmas tree business has one, but it really cleans up the trees well.

Select a good place for the tree. The first consideration is accessibility to the tree. Beyond that, the tree should be kept away from heating registers, which may tend to dry out the tree, or fireplaces, which could ignite the tree with embers. Actually, the chances of a well-cared for tree catching fire is pretty slim, but you should obviously take precautions.

Select a proper tree stand. There are a lot of cheap, lightweight tree stands on the market. You can even buy them in plastic now. Many of these aren't really adequate for a tree of any size at all. If you have a seven- or eight-foot scotch pine, you've got a lot of weight there, and it's going to be difficult to keep the tree upright in a lightweight stand.
There are several good Christmas tree stands available. It is recommended that tree stands that have a five- or six-inch spike. With these stands, the Christmas tree business will drill a hole into the base of the trunk, and the tree fits down over the spike. Another good stand for a large tree uses guy wires that attach to screws drilled into the tree a couple of feet above the stand.

On bigger trees it is recommended that people try to tie them to a window frame or a wall with fishing line or fine wire. It really makes a difference on those bigger trees.

Make a fresh cut: Just before putting the tree in the stand, be sure to cut about one inch off the base of the tree. Since pitch tends to seal the trunk off, this opens up new wood and the tree can absorb the water.

Keep the tree properly watered. Most people understand this, but it's easy to let a tree dry out. Other than spruce trees, fresh trees that are well cared for should last for the entire holiday season, and a well-watered tree keeps its fragrance much longer.

Trees require large amounts of water for the first week or two. Homeowners should check the tree at least once a day and probably more often for a larger tree. What happens is the tree is dormant when they take it inside because it is winter. When the tree is moved inside where it's warm, after a day or two the tree thinks it's spring and begins to grow. That's when they take up a tremendous amount of water.

If the tree stand runs out of water, the tree forms a cap of sap over the bottom of the trunk and no more water can move into the tree, which will cause the tree to dry out. If this happens, the tree should be taken out of the stand and a fresh cut made on the trunk.

According to the National Christmas Tree Association, research has shown that ordinary tap water works better at keeping a tree fresh than commercial products, home-brewed concoctions or distilled water. Average-sized Christmas trees can absorb up to a gallon of water a day.

Store the tree properly: If the tree isn't going to be used immediately, it should be stored in a sheltered area in a bucket of water so that the wind and sun don't dry it out.

Source: http://news.uns.purdue.edu/