Here are a few:
(credit to Tom Garnett, Beth Dooner, or Oliver Facey)
!
From the top, we have:
Druj charging in a disorganised mass.
Jotun fighting Wintermark
Jotun taunting the Imperials (who could possibly be playing that Orc at the front?)
Druj spotting a vulnerable spot and charging
Vallorn Husks emerging from the woods ('cos it’s not just the orcs…)
And Freeborn vs Grendel
(no good Thule photos for a while… 
)
My monster kit starts off with a grey/brown/tan shirt, some generic grey/green trousers, and customises from there. For the Grendel I have a purple top with sharks painted on flags on the sleeves, and several ornate sashes. For Jotun I have a red top to go under some generic armour. For Druj I have a green top. For Husks I have my last characters tabard 
For Thule I’d pack a mid-blue top.
This all makes up functionally a carrier bag of a few spare shirts, all of which I could wear under my usual kit if needed, as an extra layer. What I am guilty of (and this is likely too much) is bringing weaponry to monster with. A spare monstering sword is likely fine (if your IC one is distinctive). Monstering shields, armour, and crossbows is probably pushing it.
Basically: Barbarian orcs in Empire are colour coded (for your conveniance). A few shirts or plain tops (reccomend polonecks)in the right colours is pretty much all you need. A hunt through some charity shops can be a good start.
Extra tags, decoration, some thin black gloves and a scarf… help, but are not essential.
As with character kit though, there’s no upper limit on what you could wear, and for the same reason. PD seem quite keen to develop the barbarians; so they feel less like [disposable orcs numbers 1 to 500] and more like [Nation N#12, Gutkicker Tribe of the Druj Animosity, with full command structure, combat specialists, healer corps, and their own objectives for the battle].
