Decision making is often considered one of the most important aspects of human performance regardless of the context or environment. This notion can be evidenced by the expansive related industries that have developed, along with countless training programs and practitioners dedicated to this field. To better understand the multifaceted components of this area, it is important to utilize mixed methodological research designs that factor our underlying neurobiology, as these are critical to advancing this area and providing a comprehensive understanding of decision making. This chapter will explore complex systems analysis, subjective and objective data standards, factors of human variation, the importance of team science, and the neurobiology of decision making which informs judgments. The chapter will propose that decision making should be approached from a 'brain first' complex systems perspective that allows for comprehensive support and optimization of human performance.