@Hekimpd: Thank you! The weathering was indeed mostly done with pigments. I'll try to summarize my method.
After priming with Vallejo Panzer Grey, I try to make the uniform colour a little more interesting by applying a slightly blueish filter and, after drying, various oil colours (green, tan, pink) as small dots and then worked into the base-colour with turpentine-moistened brush.
Then comes a clear satin varnish to protect the base-colour, followed by pin-washing with MiG Dark Wash. To enhance little details like rivets etc., I apply some dry-brushing with medium grey oil-colour. The model looks quite unnatural at this point, but the effects get toned down in the subsequent weathering with pigments.
For pigments, I use various brown and ochre tones to make it less uniform, diluted in Thinner for Washes and applied in spots where I feel dust would gather in real life. After the thinner has evaporated, I take off the excess pigments with a dry or slightly moistened paintbrush. When I'm happy with the result I fix them in place with Pigment Fixer. I use a medium-sized brush and try to apply the minimum amount of fixer, letting capillary action do most of the work. That way, the pigments stay more or less as they were.
Finally, I do some dry-brushing with gun metal (AK True Metal wax) on parts that are heavily used, like handles and arm-rests, to simulate worn-off paint. Then I tone down the steel effect a bit with black pigment applied with a rubber brush.
With a complex vehicle such as this one, I do the weathering of the chassis before adding the superstructure, as it would be very difficult to reach certain parts.
24. June, 10:21