After breaking parallel, you must first push against the bar. After all, the bar is what we are trying to raise. Unfortunately, you see many lifters who push with their feet first. This causes you to bend forward Into a good morning position, which is opposite of what you are trying to achieve, in addition to being dangerous. When your back bends, you are likely to miss a squat or get injured.
Most people think of squatting as a multi-joint muscular action.
I see it as flexion of the spinal erectors and hip flexors and slight flexion of the knees. As far as equipment, in a meet, wrap the knees toward the inside. This means wrap one clockwise and the other counterclockwise. This helps to stabilize them. Wear a suit that allows the knees to be forced outward ad the glutes to be pushed out to the rear.