Contractors (electricians, plumbers, etc.)

If you work with a regular contractor who cuts you a break from time to time, you may be compelled to offer a tip. Most of the time it isn't necessary to tip an electrician or plumber, Mayne says. "However, if they do anything extra or spend more time than expected, a tip is always appreciated, with the minimum being $20."

In-home health care worker

Before tipping an in-home health care worker, it's a good idea to find out the policy of the employing agency. Many companies don't allow their personnel to accept cash tips, Mayne says. But "if the home health worker is independent, anything the patient offers would probably be appreciated. In either case, small gifts with a value under $20 are generally allowed."

Road service provider

In some cases, you may want to tip a road service driver when you don't have to pay out of pocket to cover the costs of jump-starting a car or fixing a flat. This might apply to members of AAA or similar roadside assistance programs. According to AAA, its road service employees can and do accept tips. A range of $10 to $20 is a safe bet.

Cable/satellite installer

With the high price of cable and satellite service, a tip is likely the last thing on your mind. But if the technician's beyond-believable service warrants it, and you've got it to spare, offer no more than $20.

Movers

For a local move (with no broken dishes), Mayne says $20 per mover is fair. If it's long distance, consider offering more.

Postal carrier

People often show their love for the mail carriers of the world around the holidays. But no matter the time of year, civil servants in America are forbidden by law to accept cash gifts. According to Mayne and others, you may offer your mail carrier a gift valued at no more than $20. "A gift card, a coffee mug, cookies, something that doesn't have high value," she says. "You don't want to get them in trouble."

Stacy Julien is a writer and editor at AARP Media.

Also of interest:

• 8 ways to save money this winter.
• The worst-rated states for retirement.
• 10 secrets to holiday savings.

Remember to go to the AARP home page every day for tips on keeping healthy and sharp, and great deals.