This list is proposed as a code of conduct for general officers, but I think it has some solid guidance for civilians, as well.
The best managers I ever worked for or with took on a proprietary outlook with respect to their work obligations to the company, and, more importantly, to their obligations to their subordinates and co-workers. They made efforts to ensure that their people understood their roles in the company, how they were contributing, and worked to see that they developed in their profession, and understanding of the business. They challenged authority when they thought there was a problem, but always worked to make their superiors look good. At the mess tent, they always ate last, to make sure everyone else got fed.
In short, they acted like leaders, and not just supervisors.
And George Marshall is a good role model for anyone.