Trees look much smaller out in the open, and it's difficult to eyeball the correct size. Check to see if the tree is fresh. A dried-out tree will never recover and is a fire hazard. Bounce the tree gently on the ground, or shake the tree. It is normal for some brown needles to fall out from the center, but if green needles shower off the tree, keep looking.
Wrinkled bark is another sign of a dry tree.
Break a few of the needles. Fresh trees have flexible needles that are slightly sticky when broken. Avoid over trimming the tree at the lot. If you have to hack the top or bottom off your tree, it may end up looking out of proportion. Trimming back the width can also significantly alter the shape of the tree.