You should probably start using more colors in your images, example : Make a picture with light blue, and dark green, when you have Primary and Secondary colors it makes the images look more like a scene. You did good on the background, but your focal points lighting isn't as accurate, the flow in this image is good, (Don't mean offense) This picture is lacking in Lighting, colors and Depth. I'm not saying make your designs with 50000 colors, just a Primary and Secondary color. three color maximum. If you can't seem to correct the lighting on the image, just make a light source for where the focal point is at it's brightest.