For this model I decided to apply the dust only to the lower hull and to the running gear. Although in the real life the dust usually covers the entire hull —and sometimes even part of the turret— I chose to do so to not hide the details and the color effects.
I took a vague inspiration from this photo.
(Only for discussion purposes)
I used African Earth, Light Dust and Concrete pigments, all of them by Mig. I applied them with a soft paintbrush, with vertical strokes on the side panels and on the lower hull, fading them upwards. On the road wheels I acted with circular movements, fixing the pigments afterwards with turpentine; I did this in order to achieve a less "dusty" effect and to not cover too many details. I also simulated some streaks on the lower hull with a small brush soaked with turpentine.
I applied the same pigments to the tracks, but only after a dry brushing with steel color on the treads. As shown in the first photo, modern tank tracks don't rust, owing to the high carbon content of the steel they are made of.
Finally, I dry brushed the tow cables with Model Master 1780 Steel and Humbrol 113 Matt Rust enamels, followed by a bit of Industrial City Dirt and African Earth pigments by Mig, fixed with turpentine.