HOW: Get a cable set-up anchored between shoulder and waist height. Perform a single arm row by driving your elbow towards your back pocket and letting your elbow bend. However, also focus on squeezing your shoulder blade back, when you return to starting position let your shoulder blade go forward as your arm straightens.
FEEL: You should feel the muscles around your shoulder blade working as well as behind your shoulder and your biceps.
COMPENSATION: Do not arch your back, do not shrug your shoulders.