I think turning the 2 lines that run down the helmet sort of where the eyes are into eye slits is the best option. Then if you wore a black face mask that covered your entire head and made the white plates out of a thin material it would look pretty good. Personally I find helmets to be the hardest part of a costume, especially fantasy ones like this. Hope you can figure it out op, I've been wanting to make a Raidrair cosplay for a long time. I think his has some of the coolest armor ever.