ARShooter- Make certain your bow is tuned and your arrows are straight (if you don't know how-seek professional help). Shoot at 30 yards until you groups decrease. Focus on picking a spot, form and following thru with each shot. Once you start grouping well, drop back down to 20 and see the difference.

I often practice at 40 yards. It takes a more precise shooter to group at 40. Once accomplished the 20 yard shot feels like giveme's! (I'm not saying to shoot animals at these distances!!)