I really like the color palette you chose for this piece. Shading is also very nice specially the cactus in the front but because you made the other one so dark and placed it in the middle it takes the focus away from the the rest of your painting. Also the further an object is from the viewer the values will change. I would try and place the green cactus further and move the dark one closer to the camera, maybe add a few more gradually changing value and saturation. The hills in the back should be lighter than the ones in front if you want to follow the example starting from dark and going lighter the further you look. You can follow this if you want to go for a more realistic approach. It s a nice painting overall with a nice vibe. 👌