I have made some progress with my Feral Ork Junkatrukks.
They have been undercoated.
I much prefer using a white undercoat when painting models in reds, yellows or orange. If I am going for a dark look then I will use a black undercoat.
I have also added the metal areas, by given them a base coat of black.
This will be drybrushed with Tin Bitz and Boltgun Metal, I will then touch up the white areas before painting the bodywork in reds, yellows and orange colours.