I think the yellow could be washed with Devlan Mud - but that might make it look a little too 'muddy'
It depends how fantastical you want it. You could try Ogryn Flesh (either on its own or mixed with a mid-tone brown - or even even orange - mixed with water obviously) - I'd suggest experimenting either on a piece of the model or else on a similarly textured spare part. You could also try drybrushing a different tone over the Tausept Ochre (Iyandan Darksun or another yellow mixed with a little white) before applying the wash.
As for the rest I think Ice Blue would make it look more electric, although you may have to re-apply a white drybrush to the tips of the feathers afterwards. It's hard to tell how the model 'comes together' without the shading on the body though so I'd leave the tail for the moment.
Hope this helps