I've only done this once, and it was before I got into seriously reading GC.
It was in line for a pizza place, where you shift in line as you tell the cooks to add ingredients, kind of like chipotle but pizza.
I felt like I had seen this blonde girl next to me before, so I just opened with "Hey, don't I know you?" and she lit up.
After that we played around trying to figure the mystery out... looking back she was clearly attracted.
Stupidly I walked away from the situation without moving things anywhere, but today I would have at least gotten her number, if not attempted an insta-date since it was a food joint.
I've tried "This line is so long". It was a poor choice of opener, because it sounded like complaining.
You could probably make a positive contextual opener, "I can't wait for XYZ", then shifting it towards building attraction / towards her, rather than a negative/neutral one.
Or, a neutral, contextual opener, then shift toward a compliment / something about her, as if you just noticed something mid-conversation.
That'd probably feel the most natural.
If you want to compliment her as an opener, it'd probably be best to do so in a context-driven way. Like you're in line for a concert and comment on the clothes she chose for that venue / artist.
I feel like I read on here somewhere that when girls are in line "They're just waiting for you", and that it's actually one of the best places to try things, so thanks for posting this, CuriosityKillsTheCat.
Hueman