Generally, a promoters job is to conceive an event, hire the personnel needed to make it happen, choose an appropriate venue, choose a date, advertise the event, plan its logistics (every event requires a detailed itinerary of when things are supposed to happen) and then ensure those events happen as planned.
Successful promoters are creative, and they recognize the needs and desires of the people they are trying to serve. People have plenty of entertainment options, and anything to set an event apart from the others is a competitive edge. When conceiving events, they can answer the questions, What do people want, and how do I bring it to them
