Should I use hot or cold water?
Using either is fine, just make sure it's clean.
What kind of soap should I use?
Both bar soap and liquid soap is fine to use. Soap does not have to be antibacterial to work. Plain soap and water will clean your hands just as well.
What if I don't have soap?
Of course washing hands with soap is more effective than using just water, but rinsing your hands off with clean water is better than not doing anything. You can also use alcohol-based hand sanitizers that contain at least 60% alcohol.
How long should I wash my hands?
To be most effective, scrub for at least 20 seconds when washing your hands. Make sure to clean under your fingernails too.
How should I dry my hands?
Either towel drying or air drying is fine, but make sure your towel is clean. If you're in a public restroom, using a paper towel to turn off the faucet or open the door can minimize germ exposure after you wash your hands.