There is only one thing to add: Remember.
When you are talking, listen, and remember. If she mentions that she is going to something/somewhere, remember that she should something. You don't have to remember what exactly it was, but when you talk afterwards you can ask about it.
That and paying attention.
Also, disregard what TizzytheTormentor said.
Do not be their friend, be their potential partner. Girls whom you have no interest in in that way, those can be your friends. And the girl you like, her friends, they can be your friends as well. But her, never her. In both your mind and hers, you must never just be a friend. That what people call the friend-zone. It is more than possible to climb out of there, but why not avoid it entirely?