but i dont know her from school or anything
there's no level of familiarity except the fact that she's friendly and decided to give her number
stalk her in a not creepy way (online) and figure out what she likes. or if you guys are following each other on sns figure out who's she's following what she's liking and find something to bring up there..? like if she liked a local place or something tell her that you've been wanting to check it out for a while or something and ask her to tag along