I personally believe that the biggest problem we face in the service industry is that our society believes that, "the customer is always right." I say the customer is NOT always right, but that does not mean you should tell the customer that they are wrong. You generally only see a difficult customer when there is a complaint. Yes, there is a whole range of difficulties from bratty children to pompous jerks, but even they are civil. We've all had them. Some people feel like the world is coming to an end because there is ketchup on his burger or because a steak isn't medium well it means she can publicly humiliate you, even if you're just the food runner bringing the food to the table. People will complain about anything and everything. If it is too salty (though it wasn't salted at all), if it's too green, too hot/cold. It is unbelievable.
Customers don't mind paying you in pennies or having massive complicated orders. The customer doesn't care what it costs to change their mind even after a steak has been cooked. Many times as a server you may get stiffed as the cooks put too much dressing on the chopped salad. These are the difficult customers I am talking about. You are sure to get put through the gauntlet of complaints at some point in your career. I try my best to blog about information that isn't always written about, like the importance of good shoes or listening, but there is a lot of good information written on handling difficult people and customers in general. I usually generalize people into one of a couple categories, mainly people who are reasonable and people who are unreasonable. My logic is that the reasonable people will work with you to solve any problems or understand it wasn't your fault necessarily, and are willing to compromise. Unreasonable people don't care, demand perfection, and get angry with every chance they get. There is no pleasing an unreasonable person and believe me you will know the difference and it won't be hard to determine if your guest is cool or not.
Always remain calm.
Don't blame the customer.
Listen to the complaint and then fix it.
Tell a manager if you need to.
Don't put it off, that just makes it worse.
Thank them for allowing you to fix it.
Try to go beyond the expectation to resolve any issues.
Remember that it is only a temporary situation and they will be gone in a little while, hopefully sooner than later. Keep calm and don't let the pressure pull you apart. Learn from your mistakes. Take responsiblility when you make an error. Fix things before they become huge issues that requires management intervention. When you get off work go relax. Blow off some steam doing something. Tell someone about it. Working in a restaurant can be extremely stressful, and if its not one thing its another.