First, use google to find a volunteer agency around you.
Volunteer, ride along, apply for an EMT course, get your cert, start running calls, get to know your co-workers (cops, medics, firefighters, hospital staff), get to know your patient population, build up your folder of additional classes (GEMS, PHTLS, ICS, etc etc).
Come early, use common sense, stay safe, treat your patients well, take care of yourself, and don't F up. Do this for a year or two and try to apply for a job with the hospital system of your choice.