Hi Noah....well, obtain these effects isn't so difficult...so you need to use(on a base coat and relative highlights)oils,,,,and pigments.
For this tank,supposed to be on a cold region, I use Nato green (tamiya) as base coat...then I've applied selective painting with light Nato green(Green+white)....then I've studied the soviet red primer...(a type of red under the green coat)...so,with a very diluited solution I've applied the red primer (tamiya hull red+buff+light grey).
After this I've applied again a light nato green here and there to uniform the areas....then...
Oils....
Red primer oils,black,light rust.....green.
Pigment stage...... gun metal,dust,black smoke.....
and so....here the result.....Everyone could be better than mine....and I hpe to improve my skill...with patience and fun!!
Thanks for comment
(if you need better info send me a PM ;-) )
Regards....
Ciro