A data management plan (DMP) describes how you will manage your research data throughout its lifecycle, from collecting it to archiving and sharing it. Creating a data profile beforehand will help you determine your dataset's needs and potential issues, which you will address in your DMP.
DMP's can range from one page to many detailed pages, depending partly on your needs, your funder's requirements, and/or a data repository's requirements.
Metadata standards can help you decide how and to what extent to describe your actual data files. Metadata standards may be general or subject-specific.
Submitting your data to a data archive can help address long-term preservation needs and funder requirements, as well as facilitate reuse and allow for your data to be cited.
A handy rule of thumb for longer-term preservation: