This trio of images was created with Retrosupply Co.'s very cool ColorLab brush kit, which allows artists to achieve a coloring effect like old-school comic books. These three images were produced for the Retronauts podcast about retro video games. I don't always use this coloring method — which is layers of cyan, magenta and yellow with a messy black inking job on top — but the look is always distinctive and really feels like a product of the 70s or 80s.
Below are close-up images of all three illustrations so you can see how the colors are produced. ColorLab is great and has gotten an update or two since I originally downloaded the set.