From the other side of the counter, I can see it all. In no particular order, here’s a dollop of what I’ve learned from over a year of barista-ing in New York City.

1. MOST PEOPLE ARE GREAT: The majority of the people in the world are Grade-A human beings. (I’ve conducted a thorough study.)  More often than not, customers will tell you if you’ve accidentally given them too much change. They’ll return forgotten shopping bags, dropped wallets, and they’ll tip  – even when the latte you’ve handed them looks like a recently-erupted volcano. These people are the reason you get out of bed before the sun does.
   
2. COFFEE IS ART: Like in every trade, coffee is best when it’s made by someone with extensive knowledge and training. Like artists, real baristas don’t press buttons.
3. EVERYONE LOVES FLEETWOOD MAC AND HALL & OATES: Old people, young people, white people, Asian people, hipsters and gangsters — people love these bands because they’re familiar. That really exclusive indie album you’ve been dying to play? The one nobody has heard before? Oh yeah, that will flop miserably. But “Private Eyes” and “Go Your Own Way” are guaranteed to bring the house down. People will sing along and they’re most definitely going to dance. Prepare yourself.
4. THIS IS WHY YOU’RE FAT: I beg you, please put down the sugar. Oh man, for the love of God, just try it before you dump garbage into it. Please? For me? For your bathing suit? Oh, it’s OK because you got it with skim milk. My bad, carry on.
5. SILENCE IS GOLDEN: Unless someone starts chatting you up first, verbal interactions should be as brief as possible. Nothing is as unnerving as when a stranger asks you how your day is going when you’ve literally just rolled out of bed. Inside they’re yelling “OH MY GAH JUST SHUT UP AND HAND ME MY COFFEE. COFFEE, YES!” Keep things quick and easy. Anyone who enjoys small talk is not to be trusted. Throw croissants at them.
6. ESPRESSO IS NOT SCARY: There is a lot more caffeine in a large cup of drip coffee than there is in espresso drinks. When people come in acting all dramatic and exhausted and loudly announce: “Oh man, I’m going to need a  LARGE latte THIS morning!” nobody is impressed. And even worse, the huge cup of milk you just spent $4.00+ on is just that. A whole lot of milk.
7. DAYS START EARLY: It’s easy to forget when you’re young, unemployed, or just plain lazy how early most of the world gets up. But after being a barista, I realize how much you can fit into a day when you wake up at 6:15 in the morning. The early bird really does get the worm…  and the baked goods. Those always sell out by the afternoon.
8. WHITE IS A BAD IDEA: You will get dirty. You will get sweaty. White leaves no room for you to hide your shame. That, and espresso is a beeotch to get out.
9. NOBODY WILL TELL YOU WHEN YOU HAVE SOMETHING ON YOUR FACE: I can’t even count how many times I’ve chatted casually with people while I had globs of milk in my eyebrows or coffee grinds all over my face. Nobody wants to be the one to say, “Uh, you’ve got shit… everywhere…”. As a general rule, if people smile sheepishly or stare at you for longer than they usually do, it’s not because you’re looking hot in your new fedora. You’re probably covered in shmutz. Go find a mirror
10. PEOPLE ARE CREATURES OF HABIT: People know what they like and they like what they know. If your large extra-hot cappuccino aint broke, don’t fix it. That, and most people don’t like to gamble in the morning.
11. SOME PEOPLE ARE TERRIBLE: For roughly every 50 people you serve, at least one of them is bound to suck. These people will not make eye contact with you. They will mumble their complicated order while texting and then lose their mind when you don’t get it right. “Um, is this sooooyyy?” They will ask you, exasperated by your incomprehensible stupidity. Other times, these people are the ones who don’t hand you their money. They throw it on the counter, purposely avoiding your outstretched hand. Some people will try to steal, try to swindle you and haggle over prices. These people are terrible, but they’re not everyone.