Adjust so knee is aligned with the pivot point of the machine and padding on lower calf.
Contract your hamstrings to the curl pad up and towards the back of your thighs as far as it feels comfortable.
Briefly hold at that point, then slowly extend back to the starting position in a controlled manner.
Fully locking out the leg on reps.
Foot angling too far in or outwards.
Upper body moving too much.
