Cardiomyopathies are a heterogeneous group of cardiac diseases for which diagnosis and treatment are not always simple. The diagnosis of cardiomyopathy, in particular the etiology, comes from an integration between symptoms and results collected by several instrumental exams. The brain storming for the diagnosis includes also the identification of the "red flags", i.e. the pathognomonic features for each etiology that can drive the choice of appropriate diagnostic tests and therapy. In this review, we provide a step by step approach in order to help cardiologists, not specifically dedicated to cardiomyopathies, to draw the diagnosis, therapy and follow-up. This approach will be accompanied by the consultation of other specialists to discuss together the results of the exams performed and to deepen extracardiac signs and symptoms.