you need to feel out what kinda girl she is. Easily split it into 2 types... if she is fake and shallow chances are when you are being real she will not like it... those girls like games... but if you feel she has a good mind on her, than she is obviously mature and I would try by giving not overly signals of your interest in her as more than a friend. You will see if she responds. In this case I don't recommend mind games because you feel the two of you see eye to eye and that will not help.
I would wait for the right time and maybe do a little kino (touch her in a way that she will know ur intersted a bit) and than make a funny joke or something, look at her in the eyes and dont look away and then with a smile perhaps semi-serious semi-joking say along the line of "i think im starting to be into you...." or whatever you need to do what is natural for you..
Last nite I talked with my friend (who is also a bigtime DJ its always 1 after another with this guy STR/LTR doesnt matter) and we came up with an idea for my current situation... sent her an SMS saying i miss her lips and skin blah blah and she responded laughing so I left it at that...
1 thing is for sure, you need to make the switch soon because you don't want to enter the just friends world!!!!!!