i think camouflage and seasons would look really kool.
COLORS FOR CAMOUFLAGE:
blue, green, pink, orange, red, and shades (black, grey, white).
SEASONS: winter: ice, snow, christmas etc.
spring: grass and trees, flowers etc.
sumer: sun, beach, ice cream? etc.
autumn: falling leaves, orange leaves, dead trees (trees without leaves (lol)) etc.