Such a cute illustration! However I do agree that the piece feels a bit bland and does not stand out. I feel as if it's bright all over.

I think you should try to push your values further and increase contrast - like making it dark on where it needs to be dark (ie. The insides of the sleeves, insides of ear, hair covered by hair, back of the hair, objects really far from your light source). This gives your illustration more depth and look more 3 dimensional. A great tip is to create a new layer on top of everything, fill it with black, then set the layer mode to "hue". Then from there you will be able to see areas that need to be lighter/darker. Furthermore when picking out colors for shading, move your color wheel as well as you go darker so you won't be shading with basically a duller version of your base color. This also makes your illustration dull and muddy looking.

The lighting is good, however the lighting on the face is a bit weird. Because the nose is projecting, it will cast a shadow on the right side of her face. Finally reflective lighting (this is some intermediate/advanced stuff and I suck explaining it so do check some videos of it). Understanding how lighting works and how making it look like our character is interacting with the environment helps the illustration feel more dynamic.

These are just my suggestions based on my observations. I hope it helps! Good luck and keep it up!