There is no need to be rude to me when I'm being polite, smiley and doing my job perfectly. Don't act offended when I've done nothing to offend you. Don't come to the tills expecting to return something 3 years old and then have a hissy fit when you can't.
It's a silent area. Therefore, do not talk on your mobile. Do not keep sniffing, tapping, talking or eating. Listening to a personal stereo is fine so long as I can't hear it. In short, understand the concept of silence.