Wipe Down Everything
The best way to minimize germ sharing is to regularly clean and sanitize the surfaces that everyone touches. Germs have a longer lifespan than you think, so not only should desks, tables and chairs get a regular wipe down, but also computers, keyboards and door handles.
A sanitizing wipe will usually do the trick and is safer than regular applications of disinfectants. True disinfectants are in the same class as pesticides and should only be used when students aren't in the room and only if a student has coughed or sneezed at his desk.