As we enter flu season, I think that the importance of hand-washing can not be overstated for maintaining health. Here is a (somewhat ugly) flyer published by CDC:

You'd think CDC could hire some graphic designers!

Two things that I think many people don't appreciate: (1) washing hands with hot soapy water is better than using alcohol-based sanitizer and (2) you need to wash your hands for a long time to get best results.  A funny story on NPR last spring provides some ideas for timing your hand-washing.  I'm afraid I can't help but sing Bohemian Rhapsody (starting at time stamp 3:06 for 20 secs) while washing my hands ever since hearing this story...