This book draws on the author's own experience as a practitioner, collaborations with professionals from small and medium-sized businesses with international scope in North Macedonia and Belgium, and academic research. Its goal is to bring together tactical management and information systems research in complex environments. By developing the "DENICA" managerial method it re-introduces tactics as an important managerial function and underestimated source of competitive advantage. The book also offers a roadmap for dynamic reconfiguration of the managerial systems in complex environment, while considering adaptability, sustainability and effectiveness in the process. Furthermore, the book introduces a methodological "kaleidoscope" which combines IS methodology with the managerial sciences, offering a model that can be adapted and replicated to specific contexts in order to achieve fitting solutions. Real-world case studies from North Macedonia and Belgium apply these methods and illustrate their practical implications.