I used to make the ww2 models as a teenager and loved painting them with the oil paints (you need the right brand but I can’t remember the name).

I got really good at weathering them using the watered down paint cleaner/thinner that runs into the folds and produced tiny cracks in the paint and then drybrushing lighter colors over areas.

I know I got it right because a shop in England selling those Tamiya models would give me a few of the kits for one painted and showcased them. good times