One of the things I've been trying to do is put together a visual reference document for the Dawnlands. This has involved find a lot of pictures of Central Asian nomads as well as Persians and Arabs. Due to a dearth of good fantasy images, I've been relying a lot on illustrated military history books (Osprey titles), anthropological etchings, and Soviet-era photographs. I've also managed to find a small number of women in traditional dress, though the numbers are unfortunately nowhere near parity.
The big, giant, outstanding problem is finding images for the demihumans. To recap and summarise: Most dwarves and halfings are brown-skinned, going through the range of skin tones you'd find in northern India, with black hair if any at all. Voidmen (originally eladrin) are very dark-skinned like Ethiopians or Somalis. Elves have green and/or brown skin.
When I started, I knew certain elements were going to be almost impossible to find - the oval-pupils of dwarves are original to the Dawnlands. People with argyria dressed in the right clothing for the Mountain People was never going to be easy. Green-skinned elves are not that common except in my own games. The material culture of Dwer Tor probably most closely resembles the Greco-Bactrian kingdoms - think half-northern India, half-Greek - which means that it's not widely depicted in fantasy art. I am disappointed that these are difficult to find, but I understand why they are.
On the other hand, it is almost impossible to find good pictures of demihumans that are a recognisable human race that is not white. The few that aren't white are things like goblins or drow, where they have a fantastical skin tone in the first place. Otherwise, dwarves and elves and halflings appear to be a whites-only club. The few pictures that one can find are generally totally unsuitable. Either they are rough sketches done by an amateur, or in the case of the one high-quality, dark-skinned elf picture I found, it was of a half-naked elf woman who was leashed and being led through a harem. I even tried things like "Greek dwarf" or "brown skin dwarf" in Google to see if I could find a few images, but there wasn't anything.
I've said this before, but fantasy art really does live by the principle that you can be any race you want, so long as it's white. This is a shame, since it makes it more difficult to convey different aesthetics beyond the medieval Northern European and perhaps the classical era. If anything, it's these less well-known eras that need more representation because players are much less likely to have a clear idea of what things look like.
The same is true of demihumans - it'd be nice to see more non-white demihumans, even if we had to put up with stereotypical forms of dress to get them (the separate-but-equal "Every black guy in fantasy is dressed like a Zulu at a summer wedding" problem). For one thing, it would help liberate people's imaginations from Tolkien's influence, but it's also useful in world-building. You might want the PCs to encounter a society of black dwarves on their travels (especially if there are PCs who are dwarves), and having some art that you can point to and say "Here's what these black dwarves look like" would be extremely useful, especially since there are no or few pictures of black dwarves actually in existence in the real world that your PCs will have seen before to give them a clear image.