Place the pulleys at the bottom of the rack and attach handles. With feet apart, bend over and with a slight bend at the knee, reach and grab the handles with arms across the body (opposite arm to opposite cable). Don't roll the shoulders and try and have a small arch in the back.
Don't pull from the arms, but put all of your thought into your shoulders and upper back. With slightly bent arms keep going until your arms are roughly parallel to the floor. Pause and squeeze everything at the top then begin to lower.