Lose their cool
"The mistakes I see bartenders make range from improper use of a jigger to making inappropriate remarks in front of guests. Our jobs can be so demanding, stressful, and fast, but sometimes you need to slow down and think about how it looks to a guest when you are yelling at a co-worker, or making rude comments. Even made in jest, an inside joke to you might lead to an uncomfortable situation for the guest. That guest will recall that feeling when making a recommendation or a return trip, and your bar may suffer for it. -- Abigail Gullo, Compere Lapin (New Orleans, LA)
Assume customers are experts
"Many bartenders out there have become hyper-focused on using modern techniques to produce esoteric ingredients that will leave the consumer's mind blown with its almost surreal level of deliciousness. The reality is that these rockstar moments of jaw-dropping amazement are few and far between, and most guests don't know anything about gin, nor do they care. Bartenders need to place greater importance on striving to create a setting and mood in which every guest feels comfortable, welcome, and will enjoy themselves no matter what they are drinking.