Hello, Really cool western drawing. To add more depth I would really think on the light and shadow. You need to first take into account all the cast shadow of your sun ( bush, cactus, horses...). Then When you have those in place consider what your fire does light, Try to keep it contains in a small sphere of influence in order to have its effect more apparent. Everything that is not lit by either the sun or the fire should be pitch black (front bush, back of the coat...) Hope it helps.

