Thanks everyone
The rust is basically just different browns (upto the near-orange vallejo plaguebrown) and thinned down fleshwash to tie the colors together.
I used some artists crayons for making the dust and some of the rust too..
It's a nervewrecking way to paint since it looks like crap until it's finished, so you never really know how it's gonna turn out..
The mud is just pva, fine grit sand and brown paint

Lowtardog, the T80 is nearly finished, i've been busy all christmas etc but it should be done soon, need some mounting brackets for the tube they mount on the rear of the turret basically, and figure out where the discarded rounds go..