If she works at the counter?
If the counter is girl hot (a 8 or above, I would only put moves on a hb, btw) she is probably being banged by the owner or one of the pts. At this point you have to have the BEST body in the gym (better then her bf) or illustrate you have cash. Or best, BOTH.
Strategy:
1) Lift heavier then anyone in the gym (don't make stupid ass grunt noises). Illustrate your physique to her but IMPORTANTLY, make it look like you do not notice her. Make it look like you are not trying to impress her (like everyone else). IGNORE HER but let her overhear info about you, your life. This will piss her off. Weeks later, once you establish your place (as the Alpha), then you can start talking to her in a casual way (see #3)
2) Coming and Going: Dress sophisticated and hip. Wear cool jewelry (gold and diamonds) and smell the best. Don't say anything to her. Make her know you are the best, your job, your lifestyle, etc.........She will want you.
3) Weeks later, after you have ignored her and illustrated your worth. Make small talk. I would not ask her anything personal like "how long have you been working here?"
#1 But more like, "Look at that fat dude on that machine, ha...ha....." Make her laugh.
The hotter she is, the greater the competition. You can fake it. But eventially she will see through you.
Key: be the best and you get the best.