This is one of the best exercises to increase the overall size of your biceps. For this, you can either use a preacher bench or the back of your sofa (basically any surface that provides a downward incline). Hold the dumbbell in one hand using a strong underhand grip. Keep your elbows fixed to the surface and slowly curl the dumbbell up and then bring it back to the starting position. Do this for 15 reps for each arm.
3. One-Arm Tricep Extension