For researchers, there are common metadata standards and domain-specific metadata standards to consider before you start to document and manage your data. At the same time, here are some general fields across all domains that you may consider so that you will be able to back up your data in an institutional data repository and most digital repositories.
Title: A name given to the dataset or research project that procured it.
Creator: An entity primarily responsible for creating the resource or dataset.
Description: An account of the resource or dataset. Can include abstract, table of contents, access information, data processing information and methodology on how the data was generated (such as equipment or software used, experimental protocol, other things that one might include in a lab notebook), software versions and configurations, and virtually any other information that is relevant to the resource.
Publisher: An entity responsible for making the resource or dataset available.
Subject: Keywords or phrases describing the content of the resource or dataset. These can be as simple as needed or can follow Library of Congress Authority Subject Headings.
Identifier: An unambiguous reference to the resource or dataset within a given context. This could be a URL to a site, a DOI, or a unique identification code associated with the resource.
Rights: Any known intellectual property rights held for the data, including access rights and rights holder.
Type: The nature of the genre of the resource, e.g. dataset, image, text, photograph, etc.
Date: Key dates associated with the dataset including project start and end date, release date; time period covered by the data; and other dates associated with the data lifespan, e.g. maintenance cycle, update schedule.
Source: A related resource from which the data is derived, including details of where the source data is held and how it was accessed.
Relation: A related resource which can include any of the following variations: "Relation-Has Format Of," "Relation-Is Format Of," "Relation-Has Part", "Relation-Is Part Of," "Relation-Has Version," "Relation-Is Verison Of," "Relation-Replaces," "Relation-Is Replaced By," "Relation-Requires," "Relation-Is Required By."
Coverage: The spatial and temporal topic of the resource or dataset. Spatial topic and spatial applicability may be a named place or a location specified by its geographic coordinates. Temporal topic may be a named period, date, or date range. For example, coverage.spatial field value might be "36.0544° N, 112.1401° W" for the location of the Grand Canyon. A coverage.temporal field value might be "1990s" or "Neolithic period."
Audience: Class of entity for whom the resource or dataset is intended or useful.
Provenance: A statement of any changes in ownership and custody of the resource or dataset since its creation that is significant for its authenticity, integrity, and interpretation.
The above fields are all Dublin Core compliant, which will make data sharing and harvesting across subject domains and data repositories easy. However, non-Dublin Core compliant elements and domain specific information are equally if not more important to record.