STEM (Science, Technology, Engineering, Mathematics) clubs are gaining momentum as a means for engaging students in STEM-related activities. Despite this growth, there have been limited attempts to examine the conditions that inform practice in these informal educational spaces. This paper addresses that gap through a comprehensive literature review of empirical and practitioner publications, with a focus on synthesising the approaches that support STEM clubs to be effective learning environments. In total, 33 papers were included in this review. Through a rigorous literature review process, the research team identified a number of key focus areas that support the achievement of learning outcomes and programme sustainability. These focus areas are grouped into three key themes -- club management, environment, and program evaluation -- that STEM club practitioners should attend to in order to ensure a well-informed approach. Within in each theme a number of sub-dimensions were identified, which provide practical insights and lived examples of how these conditions can be enacted within STEM clubs in ways that speak to quality. The evidence-based findings presented in this paper can be used by practitioners to guide STEM club practice. Further, the paper identifies where research is required to explore contemporary practice in informal education settings.