She's nice, slightly tomboy
(Sarah seems to be full girly)
She doesn't like bullying. When the kids mess with Jimmy or even when Kevin is being a dick to Ed's.
She takes her job as a babysitter way too seriously. Even reading a union book which she probably found at her house (God know why)
She is unaware of how hot she is, and usually okay to hang out with any boy.
Towards the later season she becomes more of an airhead.