More goblins, for now another 24'll do
Then buy a shaman and either Groblog or Durburz; they are both solid leaders, and compliment the shamans well. Personally I always choose Durburz. I'd play a few games before picking up any of the beasts. Lastly: your gonna want to buy some green stuff, goblin prowlers with shields are great elites for moria, but since there are no models for them, you gotta convert your normal warriors. However the conversion is really easy to do (just give the normal model a hood and/or a balaclava).
I personally really like the gundabad shamans; they are great in smaller games against mid range heroes with not much will to resist the weapon disintegration spell.