Use shoulder-width grip with straight bar with palms facing up. EZ-bar or a V-shaped bar is better for this exercise as they put less stress on the wrist joints.
Only the forearms should move – keep your elbows in one place during the whole movement.
As every exercise involving the pulley, standing biceps cable curls are more isolated/limited than biceps curls with barbell or EZ-bar.
Isolated/limited exercises are better for muscle definition but less effective for mass building.