One of the most effective workouts for building muscle in the arms is using a training technique called "Positions of Flexion".
This basically means training each muscle group through it’s full
range of motion; starting with a compound mid-range exercise, then
moving on to an exercise that works the muscle in the completely
stretched position, and then finishing with an exercise that works the
muscle in the fully contracted position.
In
the blog post below you'll get a complete Positions Of Flexion Arm Workout (i.e. biceps,
triceps, and forearms) that you can do at home using nothing more than a
set of adjustable dumbbells.