Above is a photo of how I start a painting. Base layers first, to get layered colours and basic lighting or shapes.
As you can see, I start adding detail as I go. I wasn't happy with the houses and general direction of the detail, so I started again. This happens more often than you think! Sometimes things work, sometimes they don't!
I've lightened the sky for now and started redoing the bottom section. Once I've added more detail I'll start with the light and dark contrasts.