Daugherty said families should keep in mind that tipping customs vary by region. For example, a plate of homemade cookies may be perfect for a newspaper carrier in the Midwest, but crisp dollar bills might be more appropriate in the East.
''So I think talking to neighbors is a great idea, especially if you're new to town or to that part of the country just to see what local custom is,'' he said.
There also are legal or ethical issues. Postal carriers, for example, aren't supposed to accept cash but can accept noncash gifts valued at no more than $20, he said. And in some places, a tip to a teacher ''might be seen as a bribe,'' Daugherty said.
That doesn't mean parents shouldn't try to do something nice for their children's teachers, he added.
''You can get creative ... get together with a group of parents and pool your money for a gift certificate to a local restaurant or a local shop,'' he said.
Oliver Mims, the British-born host of Proper Ollie, an Internet TV show focused on manners, said 15 percent used to be the standard tip for regular service, say at a hair salon, but that many people now routinely give 20 percent tips.
Some people give an extra week's pay to a service provider, such as a babysitter, others might double their normal tip, he said. But Mims believes a noncash present is always in good taste.
''I think it's always fair to give a gift, especially if you've developed a relationship and have come to learn about their interests,'' he said.
Mims suggests, for example, a coffee table book about their favorite artist or, perhaps, a gift certificate for a nice dinner or to a place the person might like to visit.
One worry is whether a holiday tip given in a place like a restaurant gets shared among the various staff members — the waiter, the bus boy, the kitchen help.
''You can always try to tip them directly, but there probably are times of the year ... when tips are not fairly distributed,'' he said. ''But you have to draw the line and say, 'My responsibility is to give 25 percent — and it's up to the restaurant staff to sort it out.''
Another area of concern, he said, is a trend on the coasts for building superintendents to give residents of apartment buildings a list of people who should be tipped, including carpenters, plumbers and other sometimes-casual building workers.
''It becomes very controversial,'' Mims said. ''You worry that if you don't take care of everyone and you have a plumbing problem, the plumber will take his time coming.''
He suggests people discuss how to deal with such lists with their neighbors to try to find a collective solution.