I agree with the comments above but you have to have something ready before you open! Especially if you are just starting. Something like:

"Hi, have you seen that 7ft woman with a mohawk in here tonight?
"No"
"Ok she must have hit her head and left"

She may laugh but either way you're in.

Then ask her for advice on something ridiculous. Like your best friend is thinking of dating a woman taller than him or a bisexual woman and is a bisexual woman twice as likely to cheat than a straight one. She will respond then you can get going. Then notice something about her and tease her a little, something like "My nan has hair like yours, it's ok though. She's quite hot"

As time goes on you will feel more comfortable and relax then it will come naturally, but never go in dry.

Lines do work if you deliver them properly. Nothing wrong with having something prepared, until you are more experienced.