I've put together a mini-kitbash set and video walkthrough of a recent image I made. I walk through an overview of how I made the kit, then I create a scene with it, and finally bring it into Photoshop and explain a little bit of my process for creating a paint over.
I think this is good introductory information for anyone interested in creating similar concept/key art type images with Blender and hand painting. I've also included the kit and PSD for free in the description of the video but you can also go straight to my Gumroad and download them if you just want the assets.
Enjoy and take care!