Speaking from personal experience here. :) You can spend time guessing and hinting and making assumptions and over-analyzing, or you can just ask her out for a cup of coffee and see what she says. It gets easier with practice, I promise! and this way you can move on quickly if she says no or that she's straight, instead of pining after a girl for ages.
Well, it is extremely hard to know if a person likes you especially ifyou are gay/lesbian. The best way to know so like in any relationship is to ask her.
I would suggest you to do so subtly, because if things go wrong you might be in trouble. Initiate a conversation, ask her about her likes, hint subtly that you like women and if she responds, you have attained what you were looking for.
If not, don't get disheartened, you surely will find someone who will love you the same way you do.