>>459301
Alrighty:
Start with the stencil work
Your going to want to use flat simple vector objects the best and most authentic way is to cut it by hand from an image reference. I was lazy and used brightness contrast to get a 1 layer bitmap.

Next up is an airbrush layer. Your going to want to cut more stencils and use the blur tool on them for the fades in and out. I'd suggest 1 layer of fine detail, one for shadows and lastly one for fills. Again I failed by blurring the whole object, you only need a part of it.

Lastly you can grain merge with a paper texture or use Photoshops in house paper effects.