At Restaurants: About $1 per diner for the waiter.

At Hotels: One to two dollars per bag for the porter; service charge included for everything else at nice hotels.

Guides and Drivers: About $1 for taxis; $2 per hour for private drivers; $10–$20 per person per day for tour guides.

Dollars Accepted?: Yes; what's more, Sandy Ferguson of Asia Desk, a travel agency, discovered by chance that two-dollar bills open doors. Having gotten hold of a bundle of them in the U.S., Ferguson "almost caused a riot" in the airport when he paid that way. "Bring them to each hotel" for the porters, who consider them good luck—because of their rarity.

P.S. Ferguson says be prepared for unusually effusive thanks for a tip here. "Don't get embarrassed by that," he says.

Source : CNTraveler.com