Out of the recent 3, Tira probably is my favorite because I could see a theme or a silly story of what she is right now. A psychotic and rebellious hipster in school.
Hipster Tira
The Tira is in the right direction, but hipsters usually have more than one color imho. While blue and white is a good start, I'd probably think about changing certain parts. Instead of tacky blue boots, try experimenting with brown, cream, gray, or black to offset. As for the blue skirt and vest? One should be blue imho while the other is a different color to make her stand out. You don't need to make her a rainbow bright, just make her a bit neutral on some parts while flamboyant on others. I'm guessing you're going for the psychotic rebellious preppy look?
Jessica Porter
I liked the way she was portrayed, but she makes me think bright barbie doll look which I'm not into. Despite that, she had enough captivation make me think of her as something. However, I don't know who she's supposed to be.
Ariel
She doesn't look like Ariel imho. She has the red hair and bow, but what about the blue eyes and gentle feminine touch? The colors and outfit are way too bold for my taste and she makes me think Ariel the badass mermaid....unless that's what you're going for.
Edit: Forgot to say keep on sharing. Sorry if the critique seemed a bit rough.