Well, when I shoot at a deer I aim for the exit point. For me it is where David has his red mark, only on the far side of the deer. When I have the sight pin in a straight line to that far exit point the entrance point is set. What I want is for the arrow to enter the deer, travel through the vitals and exit right around that far front leg. The lower the exit hole, the easier the blood can drain.

the entrance point changes with each step and turn the deer may take, but my exit point is always the same...

I have had a lot of success useing this method. You will to if you can understand what I am talking about and then learn to do it.