She's kind of mean to you
This is all about playful flirting, not actually being nasty. If she teases you a little bit, she is definitely into you. If she's super, super mean to you, she probably really does NOT like you -- and we have to stop encouraging people to assume assholes are Prince(ss) Charming in disguise.
If she calls you a dork for loving Bruce Springsteen, that's teasing. If she tells you to screw off because you're a pompous asshat or belittles you in any way, she's not worth your time.
She texts you back right away
This is a sign that she feels you, and that she's a mature lady who doesn't want to play games. If a person tells you they're not a big texter, most of the time it's because they don't want to text YOU back that much. If she's texting you back all day, every day, she digs you.
Please do keep in mind that getting back to you isn't an invitation for you to send a million texts while this person is also trying to have a life, a job, friends, etc. That just gets weird.
She'll take public transportation to hang out with you
If you notice that you're in her neighborhood for every date, it can mean she's not that invested in the relationship. Someone who likes you will take any means necessary to get to you: bus, subway, Uber, rickshaw... And you ought to be returning the favor.