preparation to become graduate nurse and registered nurse

i am student nurse that will be graduate in 6 month. i'll be work at cardiac specialist hospital next year. what i am worry about the cardiac medicine and ecg interpretation. i knew that i'll be orientate before i start to work in that hospital but i want to know what is the most important thing in preparation to become graduate nurse and registered nurse soon beside having theory about cardiac disease. i need some advice and tips from allnurses about this.