As an entrepreneur, I set my own standards, and I realized I was satisfied with my performance in both of these instances. I wrote all the company policies, and guided supervisors when they put employees on disciplinary warning for not abiding by those policies. The rules and expectations were fairly clear. If you didn't follow the company's stated expectations, you were out the door. As a self-employed professional, the standards you set are mostly of your own making.
Professional associations demand compliance with ethical standards of behavior.
Other than that, you set expectations of yourself and then develop your own standards for measuring the success or failure of your efforts. Your colleagues give you a yardstick to measure yourself against, but comparisons can be misleading. When you are running a business or in the public eye, someone, somewhere will always have something critical to say about your work. You can't escape criticism, no matter how perfect you try to be. I finally learned to listen and evaluate criticism, take the best and learn from it, and leave the rest and move on.