Any ideas on how I might approach a girl working at a store?

It's a small isolated store where people rarely come in, so an unrushed 1 on 1 conversation would be possible.

I've never been to the store and I'd be a perfect stranger to her. I'd seen this girl around uni and always liked her. I spotted her behind the counter through the store window by chance while walking by. I'm not at uni any more, so I can't approach her there, this is the only option.

The fact that we don't know each other and that it's such an inappropriate context to approach a girl is what troubles me the most about this. Any ideas or thoughts?