One thing I think the current TMNT series did especially well was re-inventing April O'Neil's character.
I was never a huge fan of the original comic or cartoon, but what little exposure I had made me feel like April was kind of...dull.
Building the arcing story of the current cartoon around April's mysterious back story sure went a long way toward making her more interesting.
Heroclix Barbara Gordon because it had red hair. I picked it because it was one of the few that looked somewhat like a teenage girl. She's wearing a coat, which I decide was the coat April wore when pretending to be a pizza delivery person. I used green stuff to make it look like she has shorts.
It's not perfect: her ponytail is too high and there's no tessen, but it works!