Following CF conventions (source):

• Title: what's in the file
• History: Audit trail of processing operations
• Description of the data
  • units: units can be udunits strings e.g. 1, degC, Pa, mbar, W m-2, kg/m2/s, mm day^-1
  • standard_name: Use CF standard names
  • long_name: not standardised
  • ancillary variables: a pointer to variables providing metadata about the individual data values e.g. standard error or data quality information
  • * _FillValue, missing_value, valid_max, valid_min, valid_range
  • Dimensions establish the index space of data variables
  • Time (year, month, day, hour, minute, second) is encoded with units “time unit since reference time”

*Optional for numeric data variables

Embedded tags (tif tags):

• Spatial extent
• Temporal extent
• Coordinate reference system
• Resolution
• No data value
• Layers

For more documentation, create a README file.

Use a *.shp.xml to store the metadata in XML format (such as ISO 19115 or other XML schema):

• Spatial extent
• Temporal extent
• Coordinate reference system
• Attribute(s) meaning

Write in sheet/top lines of csv:

• Title: what's in the file
• Abstract
• Measurement details