To become an effective supervisor, you need to communicate effectively, take criticism gently and ask for feedback. An effective supervisor finds better and new ways to help his team members achieve their goals.
A supervisor must have good communication skills. A supervisor who does not have such skills could go through a difficult time aligning his team to the goals of the organization. He could also have a hard time directing how to achieve the goals. As a supervisor, you must communicate your expectations clearly to avoid confusion in the workplace.
Nobody is perfect, and your team members have weaknesses. It is your responsibility as the supervisor to point out shortcomings to the employees and correct them before things get out of hand. However, the criticism should not be negative. It should be a way of pushing the employees to achieve goals to the best of their abilities. A supervisor who does that gives his employees the opportunity to grow.
If you want to become an effective supervisor, you must know your weaknesses. One of the best ways of doing that is asking for feedback from employees. You can ask them what you can do to be more effective and the areas where they feel you are not doing well. Take the feedback positively and look for ways to improve. Encouraging and acting on feedback from employees helps them align their perception to yours.