I am playing a crusader with "blessed hammer" and "blessed shield" (I have a weapon + shield which remove the energy cost of blessed shield + let it jump 6 more times). I think I am at 360k DPS at the moment and feel like I do fine on T3 with it.

Where can I start farming? Or what should I farm for? I also still need the hellfire rings + amulett.

Thanks !

Rifts / greater rifts is where u farm for items
if u are gonna keep playing as crus, then get that blessed hammer set
a good hellfire amulet is pretty easy to get, since they all roll with socket now.

However, monk and barbarian is prefered this season, so you might want to check them out

you should farm to be ableto farm even more with better gear, to farm even more to farm
then quit

This, then save ancient pieces for the blessed shield build as you play. It's stronger once you get enough ancients.