Stand up and hold the dumbbells with your palms up (and facing forward) with you arms relaxed and to your sides. This is your starting position.
Lift the dumbbells up until your forearms are almost completely vertical. Then, lower the dumbbells back down but make sure you don't fully extended your arms straight. You should always keep tension in your biceps for maximum effectiveness.
Repeat entire movement for the desired or prescribed number of repetitions.
Perform this exercise in a smooth and fluid motion
Don't extended your arms completely on the way down
Don't swing your arms or upper body in an attempt to lift the dumbbells easier; this is cheating and does nothing for your biceps
SPECIAL NOTES & LEVEL of DIFFICULTY VARIATIONS
To increase the level of difficulty, slow down the movement or use heavier dumbbells.