6. Always tip well on the first round, and never tip with coins (unless perhaps you're in Europe).
7. Don't expect a free drink or ask what the bar's "buyback" policy is — especially before you've even ordered your first drink.
8. Don't order each individual round of drinks with a credit card — please run a tab.
9. Don't snap your fingers or whistle at the bartender to get their attention. "Lassie is not going to make your drinks."
10. Don't confuse service with servant.
11. No PDA in the bar, keep hands and tongues to yourself. Remember, this is their office — just because the lights are low and you're drinking doesn't make it OK.
12. Don't order a "slow drink" at a busy bar. Asking for something like a Ramos Gin Fizz (the original recipe requires that the drink be shaken for 12 minutes) in a crowded bar isn't going to win you any friends.
13. Don't expect the bartender to know everything about every drink that has ever existed. And no "geeking out" unless you know the recipe (and as Duff points out, "there's really no excuse with iPhones these days).
14. Don't name drop.
15. Bartenders, if you're out at another bar, don't expect special service just because you're "in the biz." And if you're visiting a friend who works behind the bar, don't expect them to have a ton of time to socialize with you. "You may be off duty, but they're not."
16. Also to the fellow bartenders: You are there to enjoy, not to have a lesson. Don't stare at the bartender's every move — you can watch, but don't stare.
17. Don't steal menus, ask if you can have a copy.
18. Last but not least, the universal rule of life holds true: Say please and thank you.