Number one is hand-washing, they say - a surprisingly effective way to prevent all sorts of diseases, including ordinary influenza and the H5N1 virus that everyone now fears may jump into humans and cause a catastrophic pandemic.
Number two is not to buy personal supplies of Tamiflu, one of two drugs shown to work against avian influenza.
The third measure is for people who are sick to stay at home.
Old-fashioned hygiene works very well, experts agree.
"You wash your hands and you cut the transmission of a bunch of diseases," says Dr Jeffrey Griffiths of Tufts University School of Medicine, Massachusetts.
This is because any type of influenza is mostly passed hand to mouth. People sneeze and wipe their noses, then touch a microwave button, for example. Or particles from a cough land on a tabletop, only to be picked up on someone else's finger.
Spread of viruses
While viruses can be suspended in the air in droplets, doctors agree they are much more commonly spread on the hands.
Alcohol-based gel or foam hand sanitisers also work well to destroy viruses and bacteria.
Improvements in basic hygiene
can help contain any outbreak
Once someone is infected, two drugs are effective - Roche and Gilead Sciences' Tamiflu, and GlaxoSmithKline's inhaled powder Relenza. Countries are stockpiling them now.
But Dr DA Henderson, who helped lead the effort that wiped out smallpox and who founded the Centre for Biosecurity at the University of Pittsburgh, said it would be a mistake for individuals to try to buy the drugs now.
"I think Tamiflu is being regarded now as the panacea of all panaceas," Henderson said.
Henderson and other experts say while Tamiflu might help cope with an outbreak of H5N1, it is not going to offer outright protection.
For one thing, stocks are limited and it will take years for Roche to ramp up production - even if, as is being discussed now, it licenses generic versions to be made by other companies.
Plus, the more widely any drug is used, the more likely the virus or bacteria it targets is to develop what is known as resistance, meaning the drug becomes less effective.
Both Tamiflu and Relenza treat a flu infection, making it less serious and perhaps making the illness last fewer days.
But they must be taken within 48 hours of the first symptoms to do any good.
They can also prevent infection with garden-variety flu if taken, for example, by a family member caring for a sick relative. No one knows if they will do the same with H5N1.
"If you were to take it as a preventative you would have to take it for probably weeks, a pill a day, 75 milligrams a day is what they recommend," Henderson said.
And the average person is not going to know when, precisely, to begin taking the drug. Many infections look like flu, said pediatrician and immunologist Dr Anne Moscona of Weill Cornell Medical College in New York.
"You wash your hands and you cut the transmission of a bunch of diseases"
Dr Jeffrey Griffiths,
Tufts University School of Medicine, Massachusetts
"If you have Tamiflu at home and you take it for a cold or give it for a respiratory virus that is not influenza, we will be unable to use these drugs when we encounter a lethal strain of flu," Moscona said.
Staying at home
If people do get sick, they must be careful to stay at home from work and not spread viruses.
"Not exposing yourself to others is the best thing you can do for public health," said Dr Chris Woods of Duke University Medical Centre in North Carolina.
But if people are forced to go out while ill, wearing a face mask would be a responsible thing to do, although it is unlikely to protect against infection.
"People have asked, 'Should we wear masks?'," Henderson said. Studies show that people usually breathe in so forcefully when they wear a mask that they end up sucking in unfiltered air from around the sides, he said.