Some photos of making light spots/watermarks and dirt with AK streaking grime.
first i made some random spots were dirt collects, after that i thinned it with the white spirit and blend it into the basecoat.
After that it was time for some streaking on the zimm. This is hard to see because i want to keep it subtile.
When the spots are dry after a day or two it is time for oils. I only used oils on the non zimmerit parts
First i gently wet the surface with white spirit and place little dots of al kind of colors on the model. this time i choose to to it random to make it colorful. There are many ways to use oils to simulate the effects you want.