Long story short: Please be nice to those who help you with your holiday shopping this year. Say please and thank you. Don't wait until you're all the way at the front of the line to rummage through your wallet for the right gift card. If you spill your latte in the fitting room, at least offer to clean it up. If the store doesn't allow food, don't bring your latte. In a store that sells food, don't eat stuff that's for sale if you haven't bought it.