There's a thread over on Ask MetaFilter about idiosyncratic public restroom habits. As I knew they would, several public bathroom habits were identified as idiosyncratic which are in fact very sensible, and should be standard for everyone. I left a comment that I think is worth reproducing here (slightly edited for clarity):

Having worked in a number of hospitals, I've had the good fortune to be taught how to use a public restroom by a series of public health experts. That doesn't seem like something that you'd need to be taught, but for most people it is. Washing your hands properly (that is, the right way at the right time) is the single most effective thing you can do to protect your health and reduce infectious disease transmission rates.

The point about public restroom hygiene is not whether urine is sterile (it is, or should be), or whether you're breathing in teeny turdicles if you can smell someone else's leavings (you are). The point is that the restroom is a collecting node, a repository, a distribution center for "germs" -- bacteria, viruses, even dangerous protozoa, but most especially viruses (flu, rhinoviruses, coronaviruses, hepatitis A and more).

Here's the protocol I was taught:

1. Do your thing; cleaning of seats (and floors) is not entirely necessary, but it's a good idea to wipe up visible liquid. If the seat is dry, seat covers are reasonable insulation against whatever invisibles are still there. Likewise washing your hands first won't hurt, but isn't necessary unless you have something dire on them.

2. Wash your hands. Wash them properly -- most of you think you do this, and most of you don't. Use soap and water; do not use antibacterial anything; take at least as long to wash your hands as it takes you to sing "Twinkle Twinkle Little Star" in your head (or out loud, if you like). Use enough soap to get a good thick lather going. Wash the backs of your hands, wash between your fingers, do each finger individually, go up your wrist at least as far as where a watch sits, scrabble your fingertips in your palms to get under fingernails.

3. Rinse thoroughly -- use all the same motions.

4. Dry your hands. If there's a tap rather than an infrared sensor, elbow tap or foot pedal (preferred options all), then turn it on before you start washing and use a paper towel to turn it off. You'll probably want to use your second paper towel, since they're pretty flimsy and the first will probably be pretty well saturated (unless you frequent a better class of bog than I do). The object is not to touch any bathroom surface with your clean hands. All of those surfaces are trying to kill you. Use the paper towel to open the door, too.

Following this simple protocol is, seriously, the most important and effective thing you can do to improve public (and your) health. If everyone does this, infectious disease transmission rates will plummet. Don't just take my word for it:

The most important thing that you can do to keep from getting sick is to wash your hands. -- CDC's Natl Center for Infectious Diseases

Posters, videos, etc from the Natl Food Service Management Inst

Hand washing is the single most effective way to prevent the spread of infections. -- Canadian Center for Occ Health and Safety

washup.org, from the Am Soc Microbiol