I hit a bit of a painting conundrum recently with regards to my Orcs. Back in the Eighties I painted the Citadel/GW Orcs and Goblins green. Not the luminous Goblin Green from GW but Humbrol French Artillery Green, a more olive green colour that looked more natural. However for the Nick Lund Chronicle Orcs I went with a terracotta flesh washed with sepia brown oil.
The problems in trying to recreate the particular looks has proven varied to say the least. I thought the French Artillery Green would be the most problematical until I discovered how Napoleon's artillery crews made it in the field (mix yellow and black and et voila!). The Chronicle brown though has been a problem.
I've tried a few experiments over the last couple of weeks and settled on a slightly darker and redder look than previous, but one I like and has a link to the old Red Goblins that existed in early Warhammer lore before being erased from history by the GW Design Studio.
The three Orcs here (all Grenadier IIRC) are painted slightly differently (Vallejo Red Black, Burnt Cad. Red and Flat Brown over a black undercoat) but the end result is similar enough and one I am pleased with so it's now full steam ahead on a unit of 21 Nick Lund Red Orcs.