Holding a dumbbell lay down on a bench with your head at the end of the bench.
With a slight bend in the arms, lower the dumbbell back in an arc motion.
Lower until you feel a stretch in the lats then pull it back to the same arc to be over your chin.
Having an inconsistent bend in the elbows.
Going too far past a strong stretch.
Rushing repetitions.
Lie down flat on a bench, positioning your head near the end. Hold the end of a dumbbell with a slight bend in the arms with an overlapped grip over your chin.
Start by slowly lowering the dumbbell back and over your head until you feel stretch in your lats and chest, then return back the same path to the start position. Keep a consistent arm bend throughout. Conduct the movement in a slow and controlled manner, focussing on the lats. Repeat for the desired repetitions.
Avoid bending the arms or over extending.