Here's the best way to do it...Locate some trees or other objects near where you think the deer might be coming by your stand location. Now range those trees STRAIGHT OUT from your stand (at the same height you are). THAT is the distance you will need to shoot if a deer walks near one of those trees. You have to shoot the linear distance (or the distance from the base of your tree to the deer).
Don't be deceived....Let's say you are 25 feet up in your stand and you use your range finder to range a deer. The reading comes back as 16 yards (or 48 feet). If you set your pin to shoot at 16 yards you may shoot over that deer because you want to shoot the linear distance to that deer which would be 13.65 yards (or 40.97 feet).