Step by Step Guide
Begin standing while holding a dumbbell in each hand at your side. Have the shoulders down and back with a tall posture.
Raise one arm up and out to the side to shoulder height with the palm facing down.
Lower that arm down.
Repeat on the other arm.
Continue alternating left and right arms.
Repeat for the desired repetitions.
One common mistake is letting the shoulders shrug up which will use the traps and neck too much. Instead, keep the shoulder blades down and back so the action is isolated to the deltoid muscles.