If possible, document data characteristics and workflows in a digital format at the time that data files are created or altered.
Create a data dictionary
DataONE's data dictionary best practice guide
Data Dictionaries (video)
Explanation of data dictionaries from a librarian at the University of Wisconsin-Milwaukee.
Electronic Lab Notebooks
A free electronic lab notebook
Guite to writing 'readme' files
Cornell University's guide to capturing key information about data in a simple text file; includes a template
Data files are more easily and accurately interpreted when they are documented using a formal, standardized metadata format.
The Digital Curation Centre's guide to metadata standards listed by subject area
Geospatial Metadata Resources
The OpenGeoportal guide to metadata tools, standards, and information for geospatial data
RDA Metadata Directory
The Research Data Alliance (RDA) list of standards by broad discipline category