As far as I know (18 year old girl) there aren't really any specific cues. As a rule of thumb, usually if she starts making (silly) excuses to spend more time with you, touching you a lot more than usual and/or starting to compliment you more than usual, and this behavior continues for a while, she might like you. But it really varies from woman to woman- can you compare how she acts around you to how she acts around other male friends? If she has any female friends, you can always ask them- they'll usually know. Bonus points if they clear out on group activities with some excuse to leave the two of you alone.