Know that EMT schools are usually run out of community colleges, hospitals or fire departments.
Call local fire departments, hospitals and community colleges to see who offers EMT classes.
Once you locate a class near you, ask the school's administration for references. Also, ask for references from previous students.
Hospitals, community colleges and fire departments often create partnerships to run EMT schools. So one may be able to refer you to another source for an EMT school.
Keep in mind that some private ambulance companies also offer EMT schools. Many will even pay for the classes, if you promise to work for them for a set number of years after graduating.