Just try the old "question-statement-question" route. For example, you'd ask her what she's doing and if she says shopping, you'd make a statement, like "Oh, spending next months paycheck on designer jeans, eh!?" or something else. She then replies and you make another statement and so on...
The idea is that you eventually come across something (music, movies, food, travel etc..) that you have in common and take it from there.
Don't forget to use some light teasing and different facial expressions when chatting. I'm amazed at how many times I see guys just keep the same face, all the way through and they look like they are attending a job interview!?! Pull a face if she teases you, pretend to walk away if she says she likes something you don't... Remember it's not WHAT you say, it's HOW you say it.
I'll give you an example. Today in Japan, I was in a men's fashion store and got chatting to this stunning shop girl (legs longer than mine, and a figure to die for!). Now her English was pretty poor and my Japanese isn't strong so if it were just down to conversation our interaction would have quickly ground to a halt, but thanks to me jokingly teasing her, pulling some faces, we really hit it off and she gave me her LINE number and we've been sorting out meeting up in the next day or so.
Girls know why guys approach them, even if it's not direct, so just be a fun, happy dude and things will work out!