i think there's too much pink going on when title and small text is all same colour.
the banding on masks is really obvious and creates a crusty look to ur shading.
notice the light source in all the references is from the side which helps define the form?
yet you've chosen an almost totally front-on light source which flattens everything.
if ur going for symmetry in the lighting then perhaps make it more overhead at least.
even a small change in light source can make a huge difference to accentuating form (try experimenting with some models in a 3d program).
if u wanna be fancy how about the masks are pretty dark except the one you've currently selected has the light shining on it?
or maybe torch-lit from underneath to add drama?
in colours there's also a barely noticeable difference between brightest and 2nd brightest white, then a huge jump between 2nd and 3rd.
try comparing their value/brightness in the colour editor you will see the numbers spike.
not saying u need to balance everything exactly evenly but you should be aware of and in control of value/brightness variance.
while ur at it its worth being aware of
HSP where P is perceived brightness (as the eye reacts differently to different colours).
This seems to be the formula: brightness = sqrt( .299 R2 + .587 G2 + .114 B2 )
example:
Colour:
Perceived Brightness:
Notice green is seen as much brighter than red despite it being considered a receding colour?
Please someone correct me where I'm wrong or point us to a more detailed (yet comprehendable) source thanks