HOW: Maintain the down dog position with your hips up high the entire time - we will only be moving our shoulder blades in this exercise. Push the ground away from you and protract your scapula. Your shoulder blades should be pushing your hips in air.
FEEL: You should feel all the muscles in your shoulder working, especially in your shoulder blades under your arm-pit.
COMPENSATION: Do not push back simply by moving your hips backwards. Actively drive your hands into the ground and use your shoulders to perform the movement.