Newt's design is very simple: she's a plain black cat with purple inner ears and orange-yellow eyes, and her only marking is a white spot on her forehead that can change between any number of simple shapes - teardrop, flame, eye, cross, star, oval, diamond, etc.

The basic prompts for Newt are all listed on her reference, but she can basically be summed up by these ideas mixed together:
-Riot Grrrl
-Wiccan Magick
-Shamanesque Witchcraft
-Grungy, dirty 90's kid

Anything that you can fit into these themes pretty much applies. Newt is a very rating-flexible character, good for really dark themes and really lighthearted, happy themes alike. She can wear ritual robes adorned in enchanted gems and commence blood sacrifices in a damp cave, or sit in a pillow fort in a Goosebumps t-shirt adorned with pizza stains and slap bracelets using a ouija board and playing Ocarina of Time. You can look at it as a difference of reality vs imagination (where she's actually just a dirty kid that pretends she's a witch) or you can think of her doing all of these things alongside each other with equal realism. It doesn't really matter.