Akio basically "stole my thunder". You need compound lifts for base and then you can add more isolated movements. I believe the "just do big lifts" crowd oversimplifies things. The big lifts can go a long way to increasing arm size but it is not the only solution. I increased arm size doing SL5x5 for 1st nine months. Note that includes the chin-up, pull-up and dip assistance exercises. After that, growth stalled although weights continued to increase.
Since then, I have been doing the following one day per week:
- Barbell Curls - 3x8
- Weighted Chin-ups - 3x8
- Standing Cable Curls - 2x5
and this two times per week:
- Lever Lifts to Front - 3x8
- Lever Lifts to Back - 3x8
- Wrist Curls/Plate Curls - 3x8
- Gripper work or other grip exercises
This latter routine is for grip and forearms and has helped me do heavy deadlifts without straps.
For last four or five weeks, I have also been doing extra Chin-ups 6 days per week as part of a HFT (a.k.a. "Grease the Groove") program.