Dave the barbarian fan art

[Markdotea]

Hey guys I just started my brand new fan art and I need some help, first of all, I have a huge problem with muscles mainly the foreArm, I always make it look like a single piece of meat! I also would like some tips about how should I paint it, I usually use some yeallowish light as a main source of light and a blue light as a secondary.
What do u guys think of the overall idea? What kind of studies would be good for me to make my artwork better?
Thanks for helping!
http://postimage.org/image/s185vd2d5/