I want to interact with a waitress
What kind of customer are you trying to be?
I want to be a good and polite one.
It's nice of you to want to be that way! Being a nice customer is always appreciated by those in the service industry. I'm sure she'll appreciate you!
She cant, im not ordering a thing. I only want to flirt with her.
It sounds like you would be disrupting her work and she wouldn't appreciate that. It's okay to flirt but you should buy something so you don't look like someone who's wasting time.