HOW: Stand with your feet about shoulder-width apart. Keep both feet entirely on the ground throughout the movement. Place your hands in front of you about shoulder height to help counterbalance your weight. Hinge forward at the hips, and bend your knees as you sink your hips down. Bring them back up and repeat.
FEEL: You should feel all of the thigh muscles and butt muscles working.
COMPENSATION: Avoid letting the knees cave in or bow out. Keep equal weight distribution in both feet, and try not to let your hips shift left or right. Keep a neutral spine by keeping your core engaged to avoid having an over-arched or rounded back.