This guide focuses on the necessary steps to prepare and conduct an online experiment. After a brief look at the history and definition of online experiments, the advantages and disadvantages of the method are discussed. The reader is then guided through a 10-step procedure for creating an experiment with the platform WEXTOR. Then, we outline the process of conducting the study, which includes pre-testing, participant recruitment, study management, and data processing. Finally, the guide gives an overview of methods and techniques that pertain to online experiments. Typical errors and best practices are introduced and discussed.