Sit down on a flat bench or military bench and grab the dumbbell with your palm up. Rest your elbow and lower arm comfortably on the inside of your leg (close to your knee). Your arm should be extended and ready for the initial lift. This is your starting position.
Lift the dumbbell up until the dumbbell is just a few inches away from your chin. Then, lower it back down but don't allow your arm to become fully extended. You should always maintain tension in your biceps by keeping your arm slightly bent at the elbow at the bottom of the exercise movement. Finally, repeat entire movement on both sides for the desired or prescribed number of repetitions.
Perform this exercise in a smooth and fluid motion
Don't extended your arm(s) completely on the downward portion of the movement
SPECIAL NOTES & LEVEL of DIFFICULTY VARIATIONS
To increase the level of difficulty, slow down the movement or use heavier dumbbells.
This exercise is one of the top exercises for shaping the biceps. This is the movement that gives you the mound-shaped bulge on your biceps. It will not necessarily build as much mass as other barbell and dumbbell bicep exercises but it certainly does wonders for shaping.
Remember that the entire point of this exercise is to "concentrate" on the movement, which means to execute it slowly and smoothly. Thus, no jerking of the dumbbell while lifting it up, and don't release the weight down too fast either. It's all about hitting your biceps with a concentrated effort.