So, as mentionned previously, I gave up on my small city. The main reason is : I need to understand what “low poly stylised” really is.
I decided to start all over, with a different aim, and a different direction :
-No more a big scene, I’m aiming for an interior scene (American 50s dinner).
-I did not start by laying out the whole scene, but I started by focusing on low poly asset design.
-No fancy lighting from the start.
-Use of orthographic view, and don’t forget the final size of the asset on the render.
-REFERENCES IMAGES, DAMN!
Let’s go :
Asset 1 : Dinner table, bench and chair
Reference

Render 1

Render 2

Render for approximation of final size

Looks ok to me. Maybe not “stylized” enough?
What do you guys think?