When I do squats, I find that my shoulders are often very sore (from the weight of the bar) afterward, and sometimes shoulder soreness becomes as much a limiting factor during exercise as the strength/endurance of my legs and trunk.
I try to lay the bar across the meaty part, far enough back that my hands have to push forward to maintain stability (if I let go of the bar it would slide off the back, NOT balance on top of my shoulders).
What can I do to prevent my shoulders from becoming the "weak link" in terms of my squat?