How do I deal with insubordination?

In the past I've been responsible for managing subordinates, and had a difficult time doing so due to my race and age in my opinion --i'm in my 20's and African American, and was that way during that time. My decisions were met with questioning, opposition, and dismissals when choosing how I wanted subordinates to function/operate constantly. I experienced being mistaken within the workplace for service employees like a delivery guy, doorman, assistant, security guard, and lower level employees of another sort, and denial when complaints were made about my unique difficulties and struggles within the workplace.

These experiences have been embarrassing to say the least, and I want to know what I should do if they are to arise in the future. I aspire to own a business one day, and management skills is a must to have for any employer from what I can see.

Any advice? How should I handle difficult employees? How should I handle being "out of control" as a business owner/authority figure? How do I correct the behavior of difficult employees? Insubordination? Have you ever experienced anything like the above mentioned? What did you do? Did you fix it? How, if so?