Next time when u are talking to her just ask her out. Nothing fancy tho. Just go grab a quick coffee or a beer, thats always a good start in my opinion. Don't make a big deal out of it, be casual and relaxed, she is already into you obviously. When u finish ur coffee or beer make sure that u are the first to leave, don't let her think that you are needy or pushy. Tell her smth like ' I really enjoyed talking to you but i gotta go, i will give u a call soon so we can continue this'. Let her some space to get more interested.
Hope it helps
Cheers
Jez