Agree on the anchor "points" (the more the better), tuned bow, being surprised by the release, keep watching the point on the target you were aiming until you see the arrow hit that point. One that I have not heard anyone talking about is the stance (above the waist). Typically when I get fatigued, my back shoulder starts to drift forward and my form has me shooting with my torso more at an angle instead of in line with the shot. I usually catch this when my shot flies left and I felt like it was a good shot. I pull that shoulder back in line on the next shot and I'm back on my mark. The amount of drift is small, but the error is almost 6 inches at 60 yards. I now make it the main part of my draw cycle. My natural anchor point and everything that follows from that is "natural" so I don't have to think much about those any more, but the posture falls off with fatigue. It's more noticeable with even slight downhill shots where "leaning forward" may actually be moving that back shoulder forward (opening up the stance). I pull that shoulder back and keep my back tension and bend at the waist and the shot hits where it should. I only recently learned I was doing this, and since then my groups have tightened up.
