A tactic that may work is to draw an H on the broadside deer and aim just below the middle section of the letter. If you connect on the center of the middle section of the letter H, just behind the front leg, a vital area hit is almost assured.

Also, people usually place shots high when shooting from a treestand. It is related to proper form when shooting. From the ground, you shoot and get set with how you feel comfortable, when in the treestand, you think you are doing everything the same, but in fact you are probably lowering your arm and anchor points, rather than bending at the waist. If possible, try practicing from a treestand, your point of impact is always a bit different (usually high) then from the ground.

One other point, then I'll be quiet. If possible, try to follow the path of your arrow from the time you release. This will come in handy when wondering exactly where you hit the animal. It will also make for better follow through and shot placement.

My .02
Brian