ORIGINAL: LBR
Same thing Pete--comes with practice. I won't be taking a 40 yd shot from a treestand at an animal, and don't recally ever having a 40 yd treestand shot at a tournament (yes, we have them--usually from a platform instead of an actual treestand though). When shooting from a stand (or downhill) remember to bend at the waist--don't try to adjust with your shoulder. The distance to the target is the same, regardless if you are level with it, above it, or below it. That can get tricky, as being up high or down low will give the illusion that the shot is farther than it actually is. For instance, if you are up a tree 30 feet and the target is 30 feet from the base of your tree, you are taking a 10 yd shot, not a 20 yd shot.
Practice from every situation you will be hunting from. If you hunt from a stand, set it up and practice from it. The same goes for a blind. Practice shooting while seated, kneeling, etc.
Chad
I've always wondered about this. In reality, the shot would be 42.42 feet, because of the angle(length squared + height squared = square root of sum). It looks like you would shoot low, but most people shoot high.