Firstly, you need to get brutally strong on your presses and pulls. This is really what’s going to drive around 80% of your arm growth and give you that size and density. This can be done by doing bench press, overhead press, weighted chins, etc multiple times a week, aiming for progressive overload. Secondly, the other 20% of growth is driven by a lot of high volume accessory movements, such as bicep curls and overhead extensions. ~ Berceste