Source: MSN Health

After shaking hands with someone, do you slather your fingers in hand sanitizer? Before using the toilet in a public bathroom, do you cover it with liner?

Bad news, germaphobe.

Your meticulous habits are likely not doing you any good.

Like the surfaces we touch and the ground we walk on, our bodies are teeming with thousands of different species of bacteria, from the Lactobacillus acidophilus lining our digestive tract to the Propionibacterium acnes populating the skin on our faces and arms.

On average, about three pounds of our body weight is accounted for by bacteria alone.

Among all those lovely microbes, of course, are a few that cause contagious illnesses, like colds and the flu. So how do you protect yourself?

Here's a look at some of the most common things we do to avoid these germs — including which ones you're better off giving up.

1. Holding your breath after someone sneezes or coughs

When someone sneezes or coughs without covering their mouth or nose, they're essentially shooting their bacteria out into the air. Sneeze particles travel at speeds approaching 200 miles per hour; cough particles travel about 50 miles an hour. If you're already within range of the nasty germs, there's little chance holding your breath will keep them from coming into contact with your mouth, nose, or eyes. It'll stop you from pulling in any bacteria hanging directly in front of your face, but that's about it.

2. Using toilet seat liners

Public bathrooms first started stocking their stalls with these flimsy, frustrating sheets shortly after a husband and wife who reasoned that toilet seats could spread infectious diseases patented their invention in the 1920s.

Thankfully, we now know this is far from true. Viruses like HIV and herpes are fragile, meaning they don't survive very well outside of a nice warm human body. By the time you sit down on a public toilet seat — even if it was recently shared by someone else — most harmful pathogens likely wouldn't be able to infect you. Plus, your skin is a pretty effective block against any meandering microbes (unless of course you have a cut or open wound there, which could allow the bacteria to get in).

While they typically don't transfer STDs, toilet seats — like most other surfaces — do carry common microbes like E. coli and infection-causing streptococcus. These bacteria won't get you sick simply by coming into contact with them, though. You'd have to touch them and then touch your unwashed hands to your mouth or eyes for them to be able to infect you.

A quick trip to the bathroom sink should take care of that nicely.

3. Avoiding Public Transit

A team of geneticists recently made headlines after their mission to document all the bacteria on the New York City subway turned up nearly 600 different species of microbes (the vast majority of which were "unidentifiable," but the screen also found traces of bubonic plague and anthrax). Not to worry: there's no plague or anthrax on the subway. The same bacteria they flagged for these diseases are also found in dozens of other, not-so-harmful microbes.

As for all that other bacteria? Almost all of it was totally harmless. Finding this out firsthand actually made study author and Weill Cornell Medical College geneticist Chris Mason less and less concerned about it, he said at a recent event at the American Museum of Natural History.After all, literally every surface in the world around you is covered in bacteria. The idea that things can be "perfectly clean" is a myth — we need bacteria to live.

"We tend to think of our homes and personal environments as these pristine places, and public ones as dirty and infested with bacteria, but you should really think of yourself as a rabbit who gets to hop between two forests," said Mason.

There's evidence to suggest that exposure to everyday pathogens — such as those carried on our skin, in our intestines, and on the bodies of pets and insects —might actually be good for you, especially if you get exposed at a young age.Which is why Mason isn't afraid to let his own young daughter ride the subway or play in the dirt. "I would advise any new parent to roll their child on the floor of the New York subway," said Mason.

4. Grabbing Door Handles with Paper Towels

Bathroom door handles and grimy subway poles seem like ripe breeding grounds for bacteria. "Holding a subway pole is like shaking hands with 10,000 people," said Mason. But is all this hand-shaking really doing you any harm?

Maybe, but maybe not.

Dirty hands can carry E. coli and other potentially harmful bacteria (see below), but most of the microbes you'll find on handrails and door handles are harmless. Plus, if you're grasping handles with towels to avoid touching them with your bare hands and putting the tissue back in your pocket or purse after you've used it, you're merely transferring the bacteria you avoiding touching in the first place to another location where you'll touch it later.

5. Fish-bumping

If holding onto a subway handrail is equal to shaking 10,000 hands, could a single handshake be so bad?

Yes, at least according to a recent study in the American Journal of Infection Control which found that much of the bacteria that we transfer to one another — which is mostly harmless, but still includes a few icky microbes like those that cause infections and diarrhea, especially if the person is sick — hitches a ride on our hands.

When the researchers compared the amount of bacteria transferred by a moderately strong handshake, a firm handshake, and a fist bump, they found a pretty clear winner. Compared with the firm handshake, the fist bump conferred about five times less E. coli bacteria; compared with the moderate handshake, it conferred about 10 times less. So take a lesson from the President and the First Lady: fist bump, don't shake.

6. Slathering Your Hands with Sanitizer

Hand sanitizer is mostly unnecessary. Mostly.

If you don't have access to soap and water — especially if you've just used the bathroom — slather on!

Not washing your hands after you've done your business can be dangerous, since you might transfer the bacteria you've touched to your eyes or face.

So long as your sanitizer has a hefty amount of alcohol (the CDC recommends only using solutions with 60% or more), it can be nearly as efficient at killing common bacteria as soap and water.

Keep in mind, though, that sanitizer won't kill all germs, so stick to soap and water when you can. Norovirus, for example, a pathogen that's most often transferred via infected food and causes diarrhea, and C. difficile, which can cause deadly diarrhea and most commonly affects older adults, are immune to sanitizing gels