Start with back in a neutral position, weight in the heels, shoulders slightly infront of the bar and bar in contact with the shins
Extend the knees back. Shoulders and hips rising at the same rate. Keep bar in contact with body
To return, soften the knees and push the hips back until the shoulder is infront of the bar and the bar is past the knees.
Once the bar has cleared the knee, flex at the knee until the bar has reached mid-shin. Shoulders and hips descending at the same rate