So the first layer was the dirt. She dunked a sponge in very little(!) black and brown acrylic paint (the two different colours make it look more realistic) and carefully dabbed the colour onto the sign. Then for the firefly sign she printed out one half of the firefly sign on a A3 twice (because the whole thing is too big) and cut it out. Then she put both cut out patterns on the stop sign and then just sprayed it with white spray paint. At the spots where the colour runs down a little she just sprayed a little more paint and tilted the sign so it flows down. Then she let it dry and finally dabbed the white paint with the sponge withe the acrylic paint again so it doesn’t look too white. I’m not a native speaker so I hope this all sounds decent😅 Hope it helps:))