Painting:
Can you paint regular skulls?
I learned by using the
GW skull transfer. Study it. Keep one for reference, then apply one to amodel. Then paint over the top of it. Add some horns and youre done.
I went Scorched brown. Bone, white. Exorcists could stay at bone. Add scorched brown ribbing on the horns.
Here's my omega marine that I freehanded the skull onto,
Gaming:
Make sure you are both playing at equal points.
Berzerkers have the problem of not having a decent cheap transport to get into combat.
Sounds like you have 10 terminators, which are generally good, but fall quickly vs lots of normal attacks, which berzerkers put out.
Shoot the hell out of them as they move across the field. Save your terminators for countercharge.