Design principles represent design knowledge and constitute a prescriptive component that is included in design theory. In design science research, the formulation of generalised and intelligible design principles that can be reused in new contexts is regarded as an important outcome. Our study has revealed that existing design principles vary in terms of structure, content, and level of abstraction. This variation and inconsistency may obstruct the reusability of the design principles. The purpose of this study is to suggest support for the formulation of design principles. In order to enhance the support for the formulation of design principles, we have suggested three guidelines, which are based on analyses of theoretical statements, existing guidelines, and existing design principles. The guidelines are illustrated by using material from a design science research project.