I started with something I already had: A green tutu from my elf costume.
From there I brainstormed several ideas:
Hula dancer: Needed: Coconut bra (white shirt underneath for me) and lei.
Mermaid: Needed: Purple top and red hair dye
Robin: Needed: Red Shirt with "R" on it, mask
Kermit: Needed: Kermit hat and green shirt
Tinkerbell: Green top, ballet flats with puff ball, fairy wings
What other ideas can you think of for my green tutu?