Standing Bicep Curls
Stand erect in a comfortable position. Using an underhand grip, grip a bar with your hands shoulder-width apart. Next, extend your arms down to full extension. Keep your elbows pulled tight into your sides as you curl the bar upward towards your chin until you fully contract your biceps. Lower the bar slowly until your arms are fully extended. Contract your biceps hard at the top of the movement and hold for 2 seconds. Vary the width of the grip on the bar from time to time. Perform the movement leaning slightly forward and bringing your chin to the bar. Avoid leaning backwards and raising your elbows.

Reverse Barbell Curls
Grasp a bar using an overhand grip. Keep your hands shoulder width apart. Let the bar hang down at arms' length in front of you. Keep both elbows fixed at your side as you curl the bar upward to a position just under the chin. Contract the bicep as fully as possible at the top of the movement. Slowly lower the weight back to the starting position. Keep your shoulders square and your knees bent slightly. Avoid swinging the weight, bending backward or forward or raising your elbows as you lift the weights.

Alternating Dumbbell Curls
Stand upright with a dumbbell hanging at arms' length on each side. Your palms should face your body (inward). Curl one dumbbell forward and up in an arc. While lifting the dumbbell, twist your wrist so the palm faces toward you. Keeping your elbow steady at your side, curl as high as possible and flex your bicep hard at the top of the movement. Lower the weight slowly following the same arc. Completely lower one dumbbell before starting to curl the opposite dumbbell. For variety, perform the exercise on a seated or an incline seated bench. You can also perform Hammer Curls using the same technique but maintain the palms facing each other throughtout the lift. Remember to lower the weights slowly.

Concentration Curls
Sit on the end of a bench. Hold a dumbbell in one hand and rest the back of the upper arm against the inside of the same leg. Support the opposite arm on the opposite leg for stability. Curl the weight up toward your deltoid without moving the upper arm or elbow. Do not allow your elbow to rest against your thigh. As you are curling, twist your wrist so your finger is higher than your thumb. Flex your bicep hard at the top of the curl and then lower the weight slowly. Resist the weight all the way down until your arm is fully extended.

Preacher Curls
Position yourself with your chest against a bench, your triceps resting on the bench, your arms shoulder width apart and bent, and your hands grasping a bar with an underhand grip. Slowly straighten your arms, lowering the bar, until your arms are fully extended. This is the starting position. In a controlled manner, curl the weight up and then lower it again to full extension. Resist the weight on the way down. Preacher curls can be done either sitting or standing. For variety, use dumbbells for this exercise. Avoid curling the weight up too high and pulling the elbows up too high on the pad.