Shoot like you were standing on the ground. Just bend at the waist, don't drop your bow arm.

I also wondered about what height does to your arrow and I noticed with my range finder, that the base of a tree I was ranging was 20yds away. I then took a range from that same tree only this time I took it level with where I was standing (18ft up) it was 19yds this makes a 1yd difference....not much. I did the same thing at 40yds and the level range was 38yds.

So what I'm trying to say is if you know the distance you are shooting, shoot the same pin you would if you were on the ground and you will be within 2yds out to 40. Just remember to bend at the waist. people have a tendency to just lower their bow arm and that will move there peep alignment with the sight and thus move your point of impact.

Good Luck hunting.