To use endearing speech and know how to motivate people

To be ready to lend a hand, most importantly to share the knowledge.

The fourth principle is to be just and considerate, they shouldn’t be arrogant and once being promoted to a leading position they shouldn’t look down colleagues. You have to examine well if they have this quality, it means they have people’s skills. If they need more skills then you can top it up. 
 

For people who have people’s skills but are less competent then you need to train them harder. Before the promotion and if it is necessary to promote them, you need to guide them well, if not your work will be affected. These are simple principles. They shouldn’t be bias, also they should have people’s skills. As such the work will flow well because they are suitable to be supervisors.