You didn't say which part of your arms are not growing. I will assume it's your bi's, as this is usually the only thing people think about.
One of the biggest mistakes that I see, is that people too often neglect their tri's. You can not build huge bi's with tiny tri's.
I seperate my bi and tri workouts because I will take each to failure, not giving me energy for the other. Heavy weights may work for some but I prefer lighter weights most of the time but with many sets for each. Once a month I will perform drop sets of 100's just to shock my bi's and tri's. For example on bi's, I will start with the heaviest weight that I can, say 160 for 10 reps, drop 10 lbs for another 10 reps....so on and so on for a total of 10 sets of 10 reps, if I can move after that, I will drop the weight all the way down and rep until complete failure.
If you've never tried them, reverse grip curls will do wonders for the under side of the bi's. I prefer to do this on a seated machine as it really tweaks my wrists.
BPP