"Human beings are at their best in bars." Alec Waugh.
The Bartender... I've known a few. Some more intimate than others. I have a standing rule with the profession. Don't drink to an excess in their presence. If I do manage to get over served, I leave immediately. I want to to come back and be welcomed, and frankly, I don't think anything leaves a bad memory more than a drunk in a bar.
If a woman tries to pick you up at the bar it's always best to leave with her. Even if you just take her to her door. Your bartender doesn't have to know and you don't have to tell him. But he'll remember when you return. He doesn't want to know anything and it would be bad form to bring it up. Instead, he'll grab the bar in fornt of you with both hands and smile, "Whadaya have?" And that's all that needs to be said about that.
Do not tell your bartender how to make a drink. Either in conversation or on anything as vulgar as the other side of your business card. If your barman is incapable, suck up what he fixed and order an idiot proof beer or glass of wine. Hopefully you'll be picked up and can leave immediately.
Do not make a meal of the nut dish. One bowl and no more than two. Same to be said for martini olives. Only women ask for more than three. Besides, you can't afford to lose that much displacement.
Get to know your barman. His past, his loves, his hopes. Often this works far better than over tipping... except in NYC. A bartender at the Union League in Philadelphia took me to a strip club where we bonded over red heads. What he called, "Strawberry Shortcake." I rarely received a free drink but he always took good care of me. I took a bar maid to a black tie charity auction in Chicago. She became a warehouse of free drinks. So much so I stopped going for fear she'd be fired.
Never forget a good bartender. In 1985, I went to Harry's Bar in Philadelphia and had one of the best gin martinis of my life. I returned to the city 16 yrs later and mentioned the bar, sadly closed, to a local who told me, "He's at the Liberty Place Westin now." I went to the Westin and there he was. "Murray, you're the only reason I came back to this goddamn city." Murray, like any man, is proud of his work and a sincere compliment goes a long way.
If you can tell a story-- tell it to the bartender. It can't be long. And it has to be your story. Not a joke. For instance, the bartender suggests a double Johnny Walker Blue and you reply, "That's like saying there goes a really good looking nun." Somebody at the bar says, "Well, that's his tale of woe" and you reply, "Sadly, there's a lot more woe than there is tail in this world." Your bartender may have heard these but they're used as simple exclamation points.
Conversation is key. I mean, why would you even be in a bar unless you wanted to converse? Which is when we're really at our best.