I'd like to add my own experience to what pls8xx said.
My work environment is complex and I make many decisions everyday that have both serious and not so serious consequences, and some of the tasks I perform have zero tolerance for errors. I don't use a single strategy to prevent errors for these decisions and tasks, but use a variety of task specific strategies to prevent the errors. What the various error prevention strategies have in common is that they each have some form of double checking of the task I just did, or the decision I just made. From experience I've found that I often make mistakes, but always catch them before they produce anything serious.
This is a mental discipline I've developed over the years and it serves me well. I don't waist energy on strategies for decisions with minimal consequences, but only on those decisions with serious consequences. As part of my professionalism, I've also learned to recognize that certain conditions and circumstances raise the consequence levels, and so require greater diligence in the decision making processes.
When fatigued, I recognize that my ability to process relevant information and to make the correct decisions is reduced. If I'm fatigued and still have to make the decisions, then I do a form of mental "load shedding" to get rid of everything in my environment that's not essential, so I can concentrate and make the right decisions. When I know I'm too fatigued to make the right decisions, then I postpone making the decisions until later when I'm more rested, and I know I can process all the information accurately.
This mental discipline is sometimes boring and tedious, but is very necessary when the consequences of a wrong decision are just too serious.