I would think that if youre new to the idea of PUA, and especially daygame. I'd say dont game the staff unless you make sure its not busy. I work in a resturant and also as a PT and its sometimes annoying when youre in a hurry and someone keeps wanting to talk to you, so pick your battles. If there are long queues, come back another day. If its quiet, and you see the person is bored then most likely they will welcome a chat.
Its different with moving targets though (Stopping someone in the street), they are usually going from A to B, so just stopping them on the street means you need to have balls and something good to ask them, opinion openers are the easiest to get a response on. But dont use the same as you would in a club, and make sure the openers need more than a simple yes/no so atleast the person needs to think a bit about it.
When it comes to closing on daygame.. I find it a hell of a lot harder than in clubs, girls are more receptive to flirting there imo. I flirt with customers that I find cute, but it isnt gaming, just easygoing flirting that im not leading anywhere so I cant really say ive been going hard at it.
Some people like daygaming, others the nightgame, but also.. if you can daygame then your nightgame is golden.
A good Opener you can use in daygame at malls etc, or even with girls at college I recently saw in the Ultimate Natural Game DVDs. Its a opinion opener where you stop a girl and tell her that your friend is somewhere (preferably far away) and that you have been given 500$ to buy something for him to give to his gf's birthday and you need some advice. Make sure to not make it a yes/no answer, make her think a bit about the answer. I tried it yesterday, worked like a charm even though it was just a friendly chat (I find it hard to escalate still, and especially daygame).
Hope my random rambling didnt make your eyes bleed, and good luck !