Be able to take any job that gives you experience on a film. Don't just think that you have to be in one department or the other, because through working on one and seeing what other people do in the movie makes you realize what your role is if you become a costume designer.
I think the silhouette of the kimono costume will become engraved in people's minds. I do think there'll be lots of red accents in the near future. For me personally, I can't see myself flaunting around in a geisha uniform but it'll make me smile when I see what others do with it.
The reward is that you can actually create a world separate from reality with a story, actors, music, and camera design. When it works it can entertain, move people and teach us all.