Hey, may I please help you a little bit with colours? It seems you colour in pictures with bright colours, and shade them with dull colours, which isn't a good way to do it.
A little suggestion I have is to lessen the saturation on the colour if it's too bright for the shading/add more saturation to the shading, but I personally perfer just dulling the colours to a more pastel palette.
Trust me; It will look better!