I'll qualify this by saying that my area is really about appropriate antibiotic use. My area of expertise isn't really in prevention, but the one big thing we can all do is wash our hands. Handwashing is critical.
In some scenarios, we have to isolate patients to prevent the spread of infection from one patient to another. For example, for C. difficile infection, that would be very important. Depending on the infection, things like alcohol gels may not work to kill spores. Again, for certain infections such as C. difficile, you physically have to wash your hands with soap and water.
These are really important physical prevention strategies. Vaccination is another key prevention strategy that we always have to keep in mind.