Getting your make up right is an essential part to playing a goblin. As a general rule we all use Snazaroo because, quite simply, its easy to put on, survives the event and comes off pretty well afterwards (except for elbows and palms it appears).
Snazaroo do many shades of green, however we advise only using one shade - Grass Green. We've just put in a big order with Snazaroo to get the big, cheap tubs of green (when costs are split it becomes cheaper than buying small tubs for �3.50 in the local joke shop) which means greening up for the first time isnt going to be a problem, as theres plenty to go around! We have been known to wear lime green in the past, but only when grass green was out of stock! Goblins that are fat (ie Frik and Duh, who have body dev) wear the Snazaroo shade Dark Green.
Costume
There are some goblins in the world that wear prosthetic ears or noses. We dont, simply because we dislike wearing them as they fall off etc due to the sheer amount of crazy stuff we do.
As for the rest of our kit, there are generally two different looks. One route is the "goblin dress" that Knox has made so famous - generally quite short, to allow for running and fighting, and made of many bits of material all sewn together. Knox's is made of teddy bear fur i think, whereas mine is made of any old bits I could find, fleece, fake fur etc. The general effect matches quite well the minimum kit requirements that CP state for the race. The alternative route is the "furry shorts" look. Basically a pair of shorts with bits of fur glued on in layers (see Duh, Lek, Bat etc). Top halves vary from simply armour (generally Darkblade creations, see Knox, Lix and Brak) to furry tops (see Nuvva, Bat and Duh). We tend not to wear expensive kit on the grounds that we'd trash it very quickly.