Service

In the service industry, there's one major trick that can negate almost all of your bad experiences. Just remember, "the customer is obviously right, but I can't help them with that and should redirect the problem to someone else." No matter what, agreeing with the customer's opinion will drastically lower the likelihood of you needing to waste brain cells.

Example:

The customer says, "I have a coupon for this," but the coupon is for a different store. Instead of arguing, just say you're sadly not authorized to cash in those coupons and they should talk to the higher ups.

Also, don't forget to always work in a way that can absolve you of the blame in case anything goes wrong. If something seems like a bad idea, just write an email to a superior and ask if you should do it that way. This way it's their fault if something goes wrong.

Basically the good old, "I was just listening to orders."