hard to tell really
one way is if they take interest in you and talk to you alot...if they ask if your taken, thats a VERY GOOD SIGN!!! Typicaly, if you just met them and they're acting like your a good friend, thats another good sign.
Aside from that...your on your own...sometimes its hard to tell someone's exact feelings cause everyone's differnt, therefore everyone's behaviour is differnt....she maybe intrested in everything you do...but it could mean she thinks your cool and wants you as a best friend or something.
Long term friends, if they like you, its harder to spot
"Love is patient, love is kind. It does not envy, it does not boast, it is not proud.
It is not rude, it is not self-seeking, it is not easily angered, it keeps no record of wrongs.
Love does not delight in evil but rejoices with the truth.
It always protects, always trusts, always hopes, always perseveres.
Love never fails. "
-1 Corinthians 13:4-8