The article is devoted to the practical application of the principles of visual analytical thinking for the problems of knowledge structuring for the ontology design and development. Visual analytical thinking refers to implementation of methodologies that use different types of diagrams to represent ideas, concepts, relationships and processes. From the well-known practically used types of diagrams, mind maps were selected as the most common, convenient and simple method for the proper formation and design of ontologies of complex domains. Mind maps reflect hierarchical relationships among concepts and allow the analyst to sufficiently deeply reflect the features and patterns of the domain with their specific relationships. Buzan formulated the idea of mind maps in the 1970s as a compact means of organizing abstracts, he later deepened and enhanced this idea, which was brought to software implementation and was widely used in various fields of education, research and business. The paper discusses the basic principles of the formation of such maps and analyzes the typical mistakes of analysts. For the first time, a classification of main errors and mistakes is proposed taking into account syntactic, semantic and pragmatic aspects. The analysis of the most common errors associated with the violation of the rules of ―good generalization‖ and reasonable minimalism is given. The article may be of interest to both intelligent systems’ developers and knowledge management systems’ creators; it summarizes ten years of experience in teaching and training visual analytical thinking skills in executive MBA programs and corporate trainings.