You're doing great and would agree with RLAJay

Body lanuage is THE MOST IMPORTANT thing you need to get right more than what comes out of your mouth, it accounts for such a huge percentage. Head up, shoulders back, friendly smile walk with purpose, without being too arrogant if you're in Tescos you need to almost act you own in. There are lots of books videos on body language and confidence if you nail that part you'll find everything else with girls so much easier, they will want to keep the conversation flowing and it makes your job easier.

In terms of conversation try to avoid interviewing her, where do you, what do you etc