I've had the pleasure and some pain, (but very little pain) of managing people in my career. I've made many mistakes, but always tried to learn from them and improve. Being human you have to recognize and understand your personal biases and take measures to neutralize them as best as possible.
Letting go of personal prejudices and trusting your people can be very hard for some new managers to do but is essential if you are to be successful. I know a lot of managers that are control freaks or can do it better, faster since they have come up through the ranks. But once you become a manager, you are no longer an individual contributor. Your job now is to get results through other people. If you insist on doing the job yourself that you've assigned to someone else, then you are not doing your job as a manager.
Getting results through other people is the essence of being a manager.