(CNN) -- With cold and flu season comes time-honored traditions for relief and prevention: Feed a fever, starve a cold. Wear warm clothes. Eat chicken soup.
To curb the spread of germs, health experts recommend people sneeze into their elbows or sleeves, not directly into their hands without a tissue.
But just because those instructions have been around for decades doesn't necessarily mean they're effective.
CNN.com looked to health experts for the latest advice on your best bets in fighting colds and the flu.
Don't: Sneeze into your hands
Generations of parents and teachers have told children to cover their mouths and noses when they sneeze or cough. The rule still applies, but now kids are being taught to aim into their elbows or sleeves.
"With little kids especially, when they sneeze or cough into their hands, they don't always wash their hands, and then they use their hands to touch surfaces or other people," explains Dr. Priya Sampathkumar, an infectious disease specialist with the Mayo Clinic in Rochester, Minnesota.
It's hoped that sneezing into the elbow will prevent the further spread of germs, for young kids and adults alike.
Do: Keep your hands clean
Keeping your hands clean is crucial to avoid getting sick, according to the U.S. Centers for Disease Control and Prevention. However, colds and flu are viral, not bacterial, so antibacterial soap doesn't help fight the illnesses, says Sampathkumar. "In some ways, they can actually be harmful, because environmental bacteria could become resistant," she says.
Washing your hands successfully may take longer than you're used to; the CDC recommends rubbing your hands for 20 seconds -- about the length of time it takes to sing "Happy Birthday" twice.
One recent study found, however, that American adults -- especially men -- don't wash their hands enough after using the bathroom. Researchers for the American Society for Microbiology found that one-third of men didn't bother to wash at all after using the bathroom, while 12 percent of women didn't.
No access to soap and water? Experts say hand sanitizers also help kill germs. And an added bonus: "During winter when you wash your hands frequently, the alcohol gels can be a lot gentler on your hands," Sampathkumar says.
Don't: Overload on vitamins once you're sick
Scientific research on the effectiveness of herbal remedies and vitamin supplements has drawn conflicting conclusions.
The therapeutic value of zinc lozenges has yet to be proved, but zinc nasal gel may have a positive effect, according to a comprehensive review of zinc studies by the Stanford University School of Medicine published in the journal Clinical Infectious Diseases in September 2007.
And, after previous studies had concluded that echinacea was an ineffective cold remedy, new research has come along to muddy the waters. A study from the University of Connecticut School of Pharmacy published in the journal Lancet Infectious Diseases in September 2007 found that the herb decreased the odds of developing a cold by 58 percent and reduced the duration by about a day and a half.
Nevertheless, once your nose is already stuffed, taking vitamin supplements is probably a waste of money, Sampathkumar says.
If you do want to take a supplement to fight colds and flu before they start, Sampathkumar warns not to overdo it: "If you wanted to take a supplement, at most you need one multivitamin a day." Mega-doses of vitamins really have not been shown to help, and they can be harmful, she says.
Do: Take it easy on the treadmill
Contrary to rumors, you cannot sweat out a cold, experts say.
In fact, too much sweating can dehydrate you at a time when you need extra fluids anyway, warns Dr. Richard Deichmann, an internist at the Ochsner Medical Center in New Orleans, Louisiana.
Still, you don't need to eliminate all physical activity. "Pay attention to what your body is telling you," Sampathkumar says. "You don't want to run the 10 miles you do every day if you're not feeling up to it, but you don't necessarily have to stay in bed if you feel up to taking a walk or doing some moderate exercise."
Don't: Overdo it with cold remedies
Phenylephrine is the ingredient in nasal decongestant, which some people take to clear up a stuffy nose. But the medication won't cut short your bout with a cold or the flu, Deichmann says. Taking it orally can cause jitteriness, rapid heartbeat or sleeplessness, he adds.
On the other hand, nasal sprays can also dry up a runny nose and will probably cause fewer side effects, but Deichmann doesn't recommend using them for more than three or four days. "You get a tolerance to it, such that if you don't keep using it, you get a whole lot of secretions," he says. "It's a big problem."
As for kids, a Food and Drug Administration panel recently recommended against giving children under age 6 over-the-counter cold medicines. FDA: We can't recommend cold meds for those under 6
Do: Eat what feels good, hot or cold
Foods' enticing smells make you want to eat them. So it's no wonder you might lose your appetite when you have a cold and your nose is stuffy.
Sampathkumar recommends the old standby -- hot soup -- to open up your nasal passages and therefore improve your appetite. But she says you don't have to stop at soup; eat other things that feel good, too.
"There's really nothing that says if you're cold you're going to get a cold. Colds are definitely caused by viruses." To that end, "if you have a child who has a cold and the only thing they feel up to eating is Popsicles ... that's perfectly fine," she says.
Here's another reason to quit smoking: Research shows a higher incidence of flu cases in smokers compared with nonsmokers, and, worse, a higher mortality rate for smokers than nonsmokers from the flu, according to the CDC.
Smokers are predisposed to get more upper respiratory infections, Sampathkumar says. "Their nasal passages, their upper airways, are somewhat inflamed just from the smoke," she says, adding that smoking can delay healing once you're sick. E-mail to a friend