i personaly thinks communication is the most impotent key while managing.
manging people is one of the most hard task. while running ann organization. understanding the employes from the very beggning, on the individuals assemnt then selection evry thing goes though a very crucial way. to know whats the best.
PDRS,360-degree feedbacks , objectives that to be agreed and marking a goal by line manager and it employee,
SMARTT all these gives an idea what is to be done
also i belive team work, coaching, learning and development, communication, motivation and planning are the most importent key componets of managing people.