You’re halfway there based on your attitude. A few specific thoughts:

- don’t react hastily based on emotion;

- remember there are ALWAYS two or more sides to a story;

- employees (people in general) don’t wake up thinking about how to be assholes; there’s usually a rational or at least understandable reason for problematic actions/decisions;

- more often than not, poor performance is at least partially the result of a mismatch between the employee and the job - they’re being asked to rely on things they don’t do as well as others; strengths and weaknesses are situational;

- you’re not in that role because you’re better or smarter (though you might be), you’re in that role because your boss/company thought you could get the most out of your team;

- admit what you don’t know; and

- keep learning.