Since Darkwing asked, I'll try to show the steps on the ceiling panels.
Besides the Astronomican Grey I added the other base colors for the panels and camouflage netting.
Then a fat wash of Devlan Mud - looks really ugly while wet.
Once dried it looks a lot better.
Then I applied some Badab Black on areas that I want to darken some more, or where I want to accent the outlines some more.
Again the difference once dried is quite visible.
Then another coat of Devlan Mud (BTW, I use a size 5 brush for that).
Then I applied some highlights, by using the original colors - white, Astronomican, Codex Grey.
Next I used a mix of Scorched Brown and Black as rust and paint chip base.
And finally Mithril for the real bare metal chips.
For the floorboards I then gave the diamond plates a light drybrush with Boltgun, to simulate the worn off paint by the scuffing feet.
That's pretty much it :)
Here the ceiling pieces are mounted.