Strong interest in graphene oxide (GO) over the past decades has resulted in significant advances toward numerous applications and progress in understanding its chemistry. A rather broad community of scientists is involved in GO research including specialists in chemistry, physics, life, and materials sciences. While this diversity is a strength, common characterization techniques, such as Raman spectroscopy, FTIR, XPS, and XRD are often misused and inconsistently interpreted. Errors in data processing and analysis often invalidate key conclusions made in research papers. In many cases, experimental data provided in different studies are difficult to compare due to the lack of standardized ways of interpretations. The purpose of this review is to clarify common misunderstandings and errors in GO characterization by the four above-mentioned methods and to provide useful recommendations for best practices in data acquisition, processing, and interpretation. It also aims to offer guidance for new researchers entering the field of GO. The review is based on the authors’ extensive experience in the field. By promoting standardized approaches, this review seeks to improve data comparability, enhance reliability in GO research, and establish a solid foundation for analyzing the structure and reactivity of GO-based materials.