I (and my collaborators) am currently in the process of releasing an open-access and open-source data set. In doing so, I've had my first brush with the semi-logical process of selecting a license to stamp on that data. To make the process of selecting a license easier for others who may be in the same situation, I'll walk through my thought process when deciding which license to pick, and which elements to include in the license.
This is only a single example; any generalizations are drawn at the reader's own discretion. (Also, be wary of taking legal advice from a physicist!)