Tipping for good service is a natural for U.S. consumers - most American adults tip for good restaurant and barista attention, housecleaning, and hair styling, among other personal services.

But not everyone tips the same, obviously, and that behavior and generosity can be explained and categorized in ways that are easier than you might think.

That's the takeaway from a new study by CreditCards.com, which states that when it comes to tipping, men, Republicans, Northeasterners and credit/debit card users are the most generous (all average a median 20% tip). Meanwhile, women, Democrats, southerners and cash users only tip about 15%, according to the study.

Here's a look at some other results from the study:

-- 27% of hotel customers always tip their housekeeper; 31% never do.

-- 29% who visit coffee shops always tip their barista; 30% never do.

-- 67% always tip their hair stylist/barber; 12% never do.

Gender-wise, men usually tip more than women, but that really depends on the service provided. Women are more likely than men to tip for hotel housekeepers, baristas and hair stylists.

Somewhat surprisingly, 20% of restaurant customers don't tip at all (most dining consumers tip between 16% and 20%, CreditCards.com reports.)

Those numbers are raising some eyebrows, too.

"I was definitely surprised by how many people tip over 15%, but I was also surprised by how many people never tip at all at a restaurant," says Matt Schulz, senior industry analyst at CeditCards.com "How is that even possible? I'm guessing they don't get very good service on their next visit."

Do service professionals agree with the CreditCards.com study results? In a word, "yes."

"I completely agree with the findings that Northeastern males are the best tippers," says Julia Manfre, a resident of Boca Raton, Fla. Manfre says when she used to bartend in a Fort Lauderdale hotel that catered to people going to on cruises, she would serve people from all over the country at the hotel. "I would always introduce myself and then ask where they were from," she says. "If they were from the Northeast, I knew I was going to get tipped 20% or higher. Consistently, the best tippers were males from Massachusetts. They were by far my favorite customers."

Others agree, even on the political side of the tipping issue.

"I think the study results tend to be true," states Phil Reames, founder of Reames Financial, in Kalamazoo, Mich. "As a self-described conservative male, Reames says he has tipped 20% for as long as he can remember and notes the gratuity issue tips over into his professional practice, as well. "In my financial planning practice I look at a lot of tax returns," he says. "I've found that conservative families tend to be more generous in their charitable giving than liberal families."

"I think it follows that liberals probably tip less as well," he says.

Guys may tip better than women, especially at restaurants, because they're more likely to pay the bill, says April Masini, an etiquette expert based in New York City.

"Men still pay for the majority of dates and this gives them more opportunity to tip," Masini points out. "Because they should want to impress the people they're dating, they're much more likely to tip more for that reason."

Masini says that stinginess and treating service people poorly is a big turnoff in dating, so when men tip well while dating, they're investing in the romantic relationship just as they would make sure they look and smell good for a date. "Tipping is a way to see who someone is and how they treat others - beyond the dinner conversation," she adds.

As for credit card users and tipping, user-friendliness may be the difference maker.

"First off, it makes sense that credit and debit card users are the best tippers when compared to cash users," notes Evan Tarver, a financial analyst at Fit Small Business in New York City. "It's much easier to tip 20% by simply writing a tip on a receipt, rather than having exact change (or even cash at all). If you have a $20 bill, and a 15% tip is $20 and a 20% tip is $30, you'll more than likely tip 15% rather than trying to get more cash and tip 20%."

Tarver says the biggest factor in tipping is likely previous work experience. "I've found that those who have worked in a service industry are more likely to tip more than those who have never worked in an industry such as hospitality or restaurant," he says.

The moral of the story? Tip better, and more often, and reward the good, diligent, and attentive service providers for their work.

"Tipping is such an important and simple way to show gratitude - and it's so often missed," says Masini. "People give money to charities - they write checks that are two, three, four and five figures for donations. Put yourself in the shoes of a waiter or waitress who gets a fat tip for doing his or her job with a smile and an extra detail or two to attention - a 50% tip for great service would make their day."

Sometimes, it's just about changing your perspective and looking at things differently, Masini says. "Try tipping someone in your life double what you normally do, and see what the reaction is - and the improvement in service," she advises. "It's a relatively cheap experiment with a relatively huge payoff all around."

As Masini puts it, "charities are awesome, but don't forget the people in your life who bring you meals, make you coffee, park your car and wash your hair."