Serious pub waitress

Me and my buddies (males and females) recently go every saturday night to this nice pub, somewhat americanroad-like (I'm italian, it's not an italian-like pub), that I started to like. So I noticed this simple but cute waitress who's working every saturday and friday there. Just to let you figure the situation out, I'm 23, and she's amost surely between 18 and 23. I already started to practice sarging around, but I'm still a newbie, and I never gamed a hired gun before, so I still didn't do a single move on her, cause I don't fucking know how to treat them xD Non-working girls are all the same patterns, but a hired gun has to show you a professional mask, thus I'm stuck.

She's a bit small, slim, valuable as hb 7,5 without doubt, also some of my male friends like her. She doesn't wear a professional smile, she always have a serious look, or a bored face, and she's somewhat hasty looking around the tables. I think she's not enthusiastic about her work, and sees it as a matter of "I've gotta do it, better do it with a serious face". The other two waitresses always smile while serving, she doesn't.

Only yersterday night i tried to pick a reaction from her, but it was just a tiny test. I was there to talk with a girl friend of mine (friend, not fiancè) and I tried to have eye contact with the target every time she came to us asking for drinks o getting the empty glasses. One of these moments, I looked firmly at her while I was telling her to bring me a glass of lemonade, and smiled with the sarge-grin I usually give when sarging (you know, the -try to seduce me smile - I learned from puas). Well, she replied with a smile between embarassment and "caught offguard", but I don't know if it's a "professional smile". She came over other times cause my friend ordered other drinks, but I didn't know how to proceed.

I'm sorry for the novel I wrote but I'm a newbie in the game, and a total newbie regarding hired guns. Hope you'll reveal some useful hints