Not only does Passport to the Pub: A British Guide to Pub Etiquette teach you how to make your way around an English public house, it's an excellent blueprint for any social environment guide. Here's a snippet about buying the barkeep a drink in lieu of a tip:
"This may initially seem like an unnecessarily convoluted and tortuous way of giving someone a tip. Most visitors, however, find the 'and one for yourself' ritual a refreshingly friendly alternative to the impersonal handing over of coins.
"Feel free to offer a drink even when the bar is busy and the publican or member of staff will not have time to consume it immediately, or even to join you at all. It is quite appropriate for them to accept your offer, add the price of their drink to your order, and enjoy it later when the bar is less crowded. On pouring the drink, even several hours later, the recipient will try to catch your eye, and raise the glass to you in acknowledgement with a nod and a smile, perhaps saying 'cheers' or 'thanks' if you are within earshot."
