Sorry Snowk I didnt understand what you meant to say. Do you mean I should use AA everywhere and use dark grayish blue lines for AA for such type of pieces who have blue backgrounds?
if you are going to use aa, you should everywhere, and also, try using an inbetween likde dark blue grey rathere than just grey as you have
I like the ground, maybe more texture on the grass though. I like the colors of sky very nice, character needs work.