The most popular varieties of Christmas trees are:
Fraser Fir, Douglas Fir, White Pine, Scotch Pine, Noble Fir
and Balsam Fir.

The most important consideration is freshness. 

Many Christmas trees are trucked a considerable distance, sometimes part way across the continent and days or even weeks may pass between the time the trees are cut and when they arrive for sale. Always ask the vendor where the tree has come from and how long ago it was cut...I'm not always sure that you will get a truthful answer or that the high school kid working part time will even know the correct  answer, but ask anyway. If possible, buy a locally produced tree. You guys in Hawaii will be out of luck there, I sup-pose...whenever possible, buy local.

Does it appear green and healthy with a fragrant smell
and moist flexible needles or is there evidence of drying
or browning? 

Avoid any trees with broken branches or damaged bark. Bounce the tree lightly on its cut end if you can or shake it. Does this result in an inevitable little sprinkling or does it produce a shower of needles? If needles rain down, you might be wise to look around a little more.

The next consideration after freshness is size. 

Make sure the tree you buy will fit comfortably in the room
and location you have chosen. Use a tape measure if necessary. 

Check the bottom of the tree. Is there enough space between the end and the lowest branches to make a slightly diagonal fresh cut? 

Cutting an extra inch off the bottom before mounting your
tree will greatly help water absorption and ensure your tree lasts as long as possible. Be sure to make this final cut just before placing it in water. If it is exposed to the air
for too long, the vessels will become blocked.

Now...let's talk in depth about tree safety.  Some things are important enough to mention twice...so don't be surprised if I remind you of these points.

Always choose a freshly cut tree. To test a tree, strike the 
stump down on a firm surface. If needles fall off, the tree is
too dry.

Consider buying a live tree instead. You can plant it later
to enjoy it for years to come. 

When you are ready to set the tree up cut off 1/2 to 1 inch 
from the bottom of the tree before placing in the stand which should be filled with hot water (not boiling, but around 130-160º F) as soon as the tree is set up.

The tree could absorb as much as a gallon of water the first day.

Use wire or nylon cord to secure the tree to the wall or 
ceiling to prevent it from being knocked over by children
or pets

Place the tree away from heat sources and, of course, from  sparks and open flame.

Always keep the tree well watered. Check and refill often.

Use only noncombustible decorations.

Check and replace any worn or damaged light sets. It is a
good practice to replace any set that is more that four or
five years old.

Use only U.L. or F.M. approved light strings; spot or
floodlights should only be used on an artificial tree; NO CANDLES!

Avoid overloading electrical circuits or creating "octopus"
connections.

Do not use cellophane. There is no way to make it flameproof.

Treat trees with a Fire Marshal approved flame retardant.

Do not use cotton batting -- including Santa's whiskers --
or paper decorations unless they have been treated with a
flame-retardant treatment.

Disconnect the lights at bedtime or when unattended

Use miniature lights that produce less heat.

Make sure there in an operational smoke detector installed  nearby.

Remove discarded wrappings and packages from the house immediately and never burn them in the woodstove or fireplace it could cause a chimney fire.

Do not burn tree branches in the fireplace - it could throw
off  a large amount of heat and cause a fire. Christmas trees also cause an oily soot which may damage the fireplace.

So there you are...all the info to buy the tree. When you set
it up, give it at least 24 hours in place BEFORE you start to
decorate. This is a really good tip. The branches will rest
into its true shape and you will have a better looking tree
when you are done.

-- Source Unknown
Christmas Tree Tips
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