Proper Exercise Technique
Sit on an bench and hold a dumbbell in each hand. Keep your shoulders square and your chest up. Press your upper back and shoulders against the bench. Let your arms hang downward with your palms facing each other. Slowly curl the weight up to shoulder level, while turning your wrist so that your thumb is on the outside. Squeeze your bicep at the top and then slowly lower the weight back down. You can also do this standing or by doing one arm at a time.
Starting Dumbbell Curls Exercise