Paraphrased conversation:
TC: Make more clothes for Tati.
Kat: I get to do official dress-up, yay~!

...But I hate coming up with clothes that actually have to be practical but still look good. TC wanted something for Tati to wear in a story that'll probably never be written wherein' the Doc 'n Tati go to an art gallery and crazy things happen. That's my excuse for the colors. On that note, don't diss the awesome orange belt. It's cool. Orange belts are cool.

I did some poking around and ended up grabbing bits and pieces of designer wardrobes to get a decent outfit that would still fit Tati the tomboy hobo. :V

Oh, and the hair colorings...um, just 'cause. She apparently finds dye in the TARDIS and plays with it. Useless trivia: Back in the day, original-concept-Tati had some colored hair strands. That got axed pretty quick. How quick? I didn't even draw it.

(Title is a random lyric from the song Epiphany by Bowling For Soup. Whenever I don't have decent titles, I just use whatever I hear/think of.)