The red neon sign in the left window says "OPEN."
If I were to paint the tubes of the neon sign with bright red paint, it would be too dark in value. So I keep the sign very light in value and paint the effect of the red light on the regions around it. Note how the red light floods the window frame and the back of the guy's head.
When a light source is both high in value and strong in chroma, one strategy to capture it is to focus on the effect of the light, not on the light itself.
I'm using an ultra-limited palette of gouache: brilliant purple, flame red, raw umber, and white in a Pentalic watercolor sketchbook.
Yes, I've been known to accidentally dip my brush in the coffee.
Earlier discussion on the blog in the post "Practical Lights"