So as a solo developer, there’s a certain restriction on what kind of art I can make. Photo realism is out of the question, and to avoid the Uncanny valley, I’ve had to look at some more indie art directions. I’ve looked at vector, isometric, cell shaded and cartoon art for my 3D game, but nothing I’ve seen in video games yet has really struck me as the art style I want. But then I stumbled on two things that made me say “that’s really cool, I want to use that.” The two things were Firewatch, and (weirdly) Impressionist paintings. These two things struck me as cool because a) Firewatch is so freaking beautiful simply because the team did clever things with light and color, and b) Impressionism doesn’t rely on detailed materials or painstaking detail on the subjects they depict. Rather they mix solid colors and blur geometry to give an impression of what is there. I found both of these really amazing, and I want to find a way to use them in my game.
So I have a general idea of what I want to create, but I’m almost utterly lost when it comes to how to do it. Any tips and pointers on the how would be greatly appreciated 
You should have a look at a game called The Witness. Read through their dev blog, they explain how they developed their art style. The Witness – Explore an abandoned island.
Here’s a blog of one of the developer www.artofluis.com