Training split and intensity is very important. If arms are an issue, do bodybuilding work on the area(ie try to get a pump and dedicate a day to just bi's tri's and the lateral head of the shoulder). Consider adding some upper body cardio such as the hand driven bike machines, speed bag, and med ball throwing exercises. Look at athletes like basketball players and boxers, just try to avoid muscular imbalances between the front and rear of the upper body. If you are set on a supplement route, keep it very mild and be careful you don't mess up hormone levels. Something mild and not androgenic, and take supporting supplements to ensure it isn't converting to dht and estrogen. This is tricky, which is why I won't name any anabolics, do not need that on my conscience. Try a natural route if you can first, like oral Capsaicin, which is a non stimulant metabolism booster that also naturally increases IGF.