Managing a group of people who all have different personalities, abilities and who may or may not interact well with each other is not an easy task and, in my opinion, to be successful you require certain qualities and skills such as:

1. Excellent communication skills. You need to relay instructions very clearly so every part is well understood in order to avoid mistakes. You also need to listen carefully to what your employees tell you. A very good way to make sure someone has understood your instructions is to ask them to repeat everything in their own words. To make sure you have received information correctly, you should say "so what you are saying is..." and repeat in your own words. This simple method avoids many misunderstandings.
2. Fairness. Human beings react badly to what they perceive as unfair. So if you delegate work to others make sure you are scrupulous in allocating pleasant and unpleasant tasks evenly.
3. Good organisational skills are essential. It is your job to coordinate the work and allocate resources. You should know where everything is and be prepared for the task.
4. Knowledge. Part of the supervisor's job is to train others so it goes without saying that you should be at least one step ahead of them.
5. Accountability. If a mistake is made by one of your team you should acknowledge responsibility every time unless they have deliberately disobeyed your instructions.
6. Efficiency. For your department to work like clockwork you should always have the next task ready to be allocated to the right person so no-one spends any time doing nothing.
7. Adaptability. Be ready to manage change efficiently as and when it happens even if you don't agree with it.
8. Social skills. You should be courteous at all times. When you have to tell someone off, it should be done assertively but politely and never in front of other people. Everyone makes mistakes and nobody needs to be humiliated. Shouting at people is not a good idea as they will become resentful and unhappy. You will get more done with a smile than with rudeness. Don't be afraid to praise your team for a task well done. The carrot always works better than the stick.
9. Diplomacy. As a supervisor you have loyalty to the company who pays your wages but also loyalty to your team who are responsible for your results. A difficult balance which requires a great deal of tact.
10. Self-discipline. As a supervisor, you should inspire respect so discretion in your private life is essential nor can you tell people off for lateness if you are always late yourself.