Hi!

How would you guys open a girl that is a cashier or at the counter in a gas station or grocery store?

Again, as for the elevator game, pretty limited time for execution.

day time I think is better to go direct

i've done this one twice i think it's ok (crashed the 1st, successfull on the 2nd)

observe something she's doing or holding
ie:

superman: hey if i tell you something funny about that book would you laugh and pretend i'm not hitting on you?

Hb: haha what?

superman: no but seriously is this book good?/ or/i read it it's pretty interesting blah, blah,
...so listen i don't do this too often but you seem nice/fun/interesting (do not compliment her on her looks) would u grab coffee with me sometime?

you come off a bit as an afc but it's direct, to the point and quick
at the very least u'll make her day

Yes you can definatly open to a girl at a cash register. Make sure you do have some time though, meaning that theres not a long line. You have to give yourself some time and not be wasting time that this girl could be dealing with other customers. Think about the relation here. You are a customer who is paying and she is a worker who has to collect your money. In order to go with the system you two HAVE TO interact. It is nothing more until you make it more but thats the base. There is no need for an opener as she is obligated to open. Just be energetic and nice, many customers just want to get through the line, you want to get to know the girl. This will make you seem different. At the end of the transaction you can ask for the number if you please. Hope this helps, just my observations from working cashier.

What he said is right. I work at a grocery store and I ask the girls at the store sometimes how they want a guy to pick them up etc. They say all the same stuff thats already posted on the forum already. Confidence, funny, flattering, nice etc. But also even if you don't close on the first interaction, just go back in there another time when their working and build more rapport. Just don't be creepy about it. Ask them how their day is going, what was the best thing that happen to them today, or ask them what they are doing for fun this weekend.

Oh and as far as openers go, I would recommend just asking either the cashier or a customer for some advice on food, desert or a recipe etc. Easy opener. Or even look in their basket and ask them about something in there. Or make a comment on it, then escalate from there. Hopefully you can move the conversation away from food to display higher value.

If you are hesitant to try it on a girl your age just practice on the older women shopping there. They love the attention plus they know how to cook already so they are more then willing to offer advice. Then from there try to take the conversation somewhere else besides food. I do this all the time at my job. Most girls love it. I am to much of a AFC to close but my co-worker closes ALL the time doing what I just said.