Wings tends to grab attention because they are missings guns.
With black guns, with gold metallics, it should counter balance that and add more contrast.
For easy highlights recipies :
1. Celestra grey (2 thin layers)
2. Ulthuan grey (2 thin layers)
3. White scars edge highlights
When wet/painting it will seems like colors are too distant, but don't dilute WS with Ulthuan grey.
Do a test miniature & wait for to dry. From tabletop point of view it will be good (and the color distance really helps for clear painting).
1. Chaos black
2. (optionnal) Chaos black + (incubi darkness OR dark reaper), ratio 2:1 on surfaces exposed to light
3. Highlight dark reaper
4. smaller/edge highlight eshin grey
Also you can maybe try steps 1 & 2, and then edge highlight with mephiston red & smaller EH with wild rider red (kinda the look from obsidian color from GW painting application). Would be balsy and a good reminder of both flaming wings and dark eldar high contrasted green edges.
Also consider giving a look to OSL tutorials
(oriented source light), it's painfull & take a lot of time at the beginning, but rewarding when done correctly.
And lastly, god those wings looks fantastic *-* I'm really jealous I didn't had the idea for my similar theme.
Frenchie, long time painter, trying to get in the 8th edition
, still converting & painting hordes of dark eldars Project log
Dark eldars ~4k points /
Battle sisters ~2k points