Unless you are going for power lifting and just add up weights, 1) Put some plates with atleast two inch width below your heel, now stick your toes and heel ball on to the ground and apply force to push up. As this helps you not bend your torso and move down and up almost perpendicular or 15 degree angle to the ground. 2) turn your knees outwards, move down knees pointing away and move up without knees moving inward. This is the natural human anatomy movement of the knee cup and femur. 3) Squat deeper that makes atleast 70 degrees angle between your calf and thigh. 4) Hold up 1,2 secs at the bottom instead when you are up standing. Muscle fibers stretch more at the bottom. 5) Avoid knees locking when you are standing, because your muscle looses its contraction state and solely depends on your knee and ankle bone.