9x9 pastel on Uart
There are two ideas that Richard preaches: 1. simultaneous contrast, and 2. value does the work, color gets the glory. I will begin with simultaneous contrast. First read the section from Richard's blog.
Basically put in my words, simultaneous contrast is the song of painting. It's about relationships. A color does not sing until it is put next to another color and it relates to it. A light yellow green might appear warm but next to a yellow orange it is now cool. That same light yellow green appears very light but when placed next to the white yellow of the sky it seems darker. (simultaneous contrast works in terms of light and dark too) In this painting look at the trees near the top right. Here, there is a play with warm and cool. I used the same value to create an opalesence/ light. Because of their relationships the colors sing.