The growing interest in individual differences within experimental psychology has led to an increased need for familiarity with statistical methods that many researchers did not receive during their training. This lack of familiarity can be challenging not only when designing studies but also when evaluating them as researchers, reviewers or editors. To fill the gap, this article provides an introduction to the literature on studying individual differences, covering the fundamental concepts of test psychology, including standardization, reliability, norming and validity. It also presents practical guidelines for developing new tests, evaluating existing tests, and combining tests to gain deeper insights. The article concludes with a listing of 11 common myths about research on individual differences in experimental psychology. This text is intended to help researchers navigate the complexities of research on individual differences with confidence and expertise.