With the powerful analyses and resources they enable, digital humanities tools have captivated researchers from many different fields who want to use them to study science. Researchers often know about the learning curves posed by those tools and overcome them by taking workshops, reading manuals, or connecting with communities associated with digital tools. But a further hurdle looms: data. Digital tools, as well as funding agencies, research communities, and academic administrators, require researchers to think carefully about how they conceptualize, manage, and store data, and about what they plan to do with that data once a given project is over. Developing strategies to address these problems can prevent new researchers from sticking with digital tools and flummox even senior researchers. To help overcome the data hurdle, we present four principles to help researchers, novice and seasoned alike, conceptualize and plan for their data. We illustrate the use of those principles with two digital projects from the history of science, the Embryo Project and the Marine Biological Laboratory History Project, and their associated HPS Repository for data. The principles, while useful for digital projects and especially for people new to digital tools and to managing data, apply beyond the digital realm, so those who collect and manage data by more traditional means will also find them useful. Most importantly, those principles help researchers design plans for data that complement the unique features of their individual research projects
