Legend

A few days pass and the greenskin horde is getting closer, some minor skirmishes have already been fought, but it won't be long before they mount an organized assault. You can hear them taunting and yelling on a regular basis.

Fortunately they seem to like to drink whatever strong brew they mix up and gets them drunk, so after a night of taunts and half-assed attacks most of them are sleeping it off during the day time. You get the idea that if you could spike this brew, you could do some serious damage. However given greenskin immune systems you would need something pretty strong. For this plan to work you need some "Silent Strike" or a jar of acid.

Barring that, you could assassinate the warchief. He would be easy to find. (The biggest and fanciest tent) This would disrupt the strong leadership to these naturally unruly creatures and most likely result in a minor power struggle while they decide who should be in charge.

You could attempt to set fire to as many tents as possible, destroy their weapons and generally cause chaos in their camp. This is probably the easier, since even if you were discovered early you could still do quite a bit of damage if you were fast enough to escape.

Finally you could avoid going directly into the camp altogether and just set up traps around the village. This is the safest course of action and will cause minimum risk to you.

You can only do one of these things though, so make your choice.