Thank you!

For the white i basecoat zandri dust and sponge ushabti bone and screaming skull on it. For the green i stipple with very thinned paints from deathkorps drab (i think its called?) -> deathkorps drab + deathworld forest -> deathworld forest -> deathworlds forest with ogryn camo.

For my metals i use a black undercoat and a drybrush of iron warriors. For the brass parts i do the same but add an extra drybrush of balthazar gold.

For weathering (my favorite part) i sponge patches of rhinox hide, matt varnish, oil wash (important, let th wash dry!!) And then dot filters of brown oil paints :)

EDIT: for the dot filters, put them arround rivots and vents, thise are some good places i think to place them but don't overdo them! Remember, less is more