This paper addresses the importance of pretesting in the design of discrete-choice experiments (DCEs) and provides a comprehensive guide for researchers to conduct effective pretests. Pretesting is crucial for improving the validity, reliability, and relevance of DCEs by engaging with target population representatives to refine the survey instrument. The authors define pretesting, outline its process, and present a practical guide and interview discussion template to help researchers conduct rigorous pretests. They also provide an illustrative example of how these resources were applied to a complex DCE on investigative genetic genealogy (IGG), a police method that uses crime scene DNA to identify offenders. The guide covers four domains: content, presentation, comprehension, and elicitation, with specific questions to guide the pretesting process. The application of the guide resulted in substantial modifications to the DCE, enhancing its quality and effectiveness. The paper emphasizes the need for greater transparency in pretesting practices and encourages future research to establish good practices in this area.This paper addresses the importance of pretesting in the design of discrete-choice experiments (DCEs) and provides a comprehensive guide for researchers to conduct effective pretests. Pretesting is crucial for improving the validity, reliability, and relevance of DCEs by engaging with target population representatives to refine the survey instrument. The authors define pretesting, outline its process, and present a practical guide and interview discussion template to help researchers conduct rigorous pretests. They also provide an illustrative example of how these resources were applied to a complex DCE on investigative genetic genealogy (IGG), a police method that uses crime scene DNA to identify offenders. The guide covers four domains: content, presentation, comprehension, and elicitation, with specific questions to guide the pretesting process. The application of the guide resulted in substantial modifications to the DCE, enhancing its quality and effectiveness. The paper emphasizes the need for greater transparency in pretesting practices and encourages future research to establish good practices in this area.