P.S. "A personal touch goes a long way in Russia," says Greg Tepper of Exeter International. "Writing a heartfelt thank-you note will be as appreciated as the cash accompanying it."

SCANDINAVIA

Tipping here is fairly formalized; either the service is included in the bill, or tipping isn't done. Taxi drivers don't expect tips, and even many porters and coatroom attendants have fixed fees and don't expect a penny more. Hotel and restaurant bills usually include service charges. Scandinavia is an expensive place, but since you won't have to shell out much more than you see on the bill, at least you know what you're getting into.

SPAIN

At Restaurants: If the service is good, round up the bill to anywhere from 7 to 13 percent and leave it in cash, not on a credit card, says Virginia Irurita of Madrid's Made for Spain travel agency. If the service isn't good, she says, "you can leave the table without giving a tip and nobody will say a word. Americans are coming here and leaving 20 percent, so some waiters are getting spoiled."

At Hotels: Tip concierges who do you a special favor 5–10 euros, cleaning staff about 5 euros a day (up front if you want them to treat you extra nice), and bellboys about one euro per bag.

Guides and Drivers: Leave guides 30 euros per person per day (up to 40 if they're really good), drivers half that. With taxi drivers, round up the fare.

Dollars Accepted? Always tip in euros.

SWITZERLAND

At Restaurants: Generally, between 5–10 percent is fair, but not expected.

At Hotels: A service charge is included in the bill, so tip the concierge $10–$20 only if he makes you a special reservation. Hand the cleaning lady $5–$10 on the spot if she goes out of her way for you.

Guides and Drivers: Really good guides get about $40 per person per small group per day, drivers half that. With taxi drivers, tip 5–10 percent or round up the fare.

Dollars Accepted? Only tip in Swiss francs.

TURKEY

At Restaurants: Ten percent or a bit more, in cash—you can't put it on your credit card.

At Hotels: "There usually isn't a service charge included in a hotel bill," says Jack Shaw, co-founder of Epic Europe Tours, a luxury adventure travel company specializing in custom travel for small groups. "The concierge tip depends on how nice the hotel is, but I would guess that five-star concierges are used to better than 10–20 Swiss franc tips."

Guides and Drivers: Taxi drivers aren't generally tipped, but rounding up works, and drivers will sometimes just take the initiative and keep the change. Private cars get $35–$50 per day, regardless of the size of the group. Tour guides get $10–$15 per day per person; private tour guides, $75 and up.

Who Else? At Turkish baths, the masseur gets $20–$25. If you charter a boat, give the crew 5 percent of the price; if you rent a boat cabin, $15 per person per day.

Dollars Accepted? Yes, and euros.

P.S. "Tipping is at one's own discretion," says Earl Starkey at Protravel International, which specializes in planning trips to Turkey. "If you are not pleased with the services rendered, don't tip. It isn't like New York, where the waiter might follow you out onto the street."

UNITED KINGDOM

At Restaurants: Service is often included; if not, tip 10–15 percent. Sometimes you'll see an "optional" charge added to the bill; make sure you're not just blindly paying it but adjusting to the level you feel comfortable with. And feel free to round to the nearest pound—up or down. Tipping in pubs is not customary.

At Hotels: Porters, 1–2 pounds per bag; housekeepers, 1–2 pounds. Go up to 5 pounds apiece at the five-star hotels.

Guides and Drivers: Tip the cab driver whatever small change you have; tipping optional for a narrated boat tour through the Thames—they'll certainly ask. Give 20 pounds per day for a guide and 10 pounds for the driver at the end of the day, or maybe take him to lunch. Not much more is expected, as Brits don't always expect to tip when they're abroad.

Dollars Accepted? Pounds much preferred.

P.S. Tipping is said to have originated in 16th-century England, and though it has since spread across the globe, England has by and large gone the way of most of Europe: Tips are included in many bills, especially in formal settings, and discretion is key in handing them over.

This article was originally published in November 2008. It has been updated to reflect new information.