Matt, the best thing i ever did for my arms, is squeeze them at the point of contraction, use a weight like GOT said that you can get 10-12 reps out of, dont make it light because you still want that muscle working, but those biceps man, squeeze the shit out of then, and when you get to the top of the movement curl your wrist outward to get an even better contraction. Watch the way Dorin Yates used to train and how he trains his clients with his HIT program, squeeze and contraction has everything to do with it