Sorry to hear you have to go...
I ended up giving it a raw umber wash last night. I drybrushed over all areas, and varied the intensity to show different dirt accumulations on differing areas of the tank. The non-slip surface allowed the wash to really stand out after the drybrush. After that, I mixed in some of my base colour, lightened it, and sprayed very very faintly over most panels, to show paint fading. Then I added a few drops of flat black to this, and airbrushed around the edges of the panels. The overall effect is very very pleasing. Tonight, I have to start on the initial detailing, etc. I still have to decide which accessories I will be adding to it. I will model a tank during maneuvering excercises, and thus a hoffman device will be there, but that's all I'm decided on for now.
It still has a looong way to go, but I'm hoping to get a lot done next week. For tonight, I'll start detailing, and I have to get around to painting the tracks, otherwise it'll take me forever to mount them.
BY the way, can someone point me in the right direction for the colour of the interior? I'm modelling it with hatches open (thankfully my figs will hide the empty interior), and I want to get around to painting those tonight as well.