Set an example. Be the kind of leader you would follow yourself. You may not know every task 100 percent, but it is essential to understand how to solve or better improve each situation. If you were promoted to become a manager of a marketing department, you have to know specifics of the work and each employee. It is you who must take responsibility for each task, and not your coworkers. Your main aim as a leader is to set an example; so for instance, if you want them to be at work on time, you should be punctual yourself.