Naming standards, metadata and coordinate reference are often overlooked, yet they are exactly what makes data combinable.
Many institutions already hold large volumes of spatial data but struggle to combine it. The problem is rarely volume; it is the absence of an agreed structure from the outset.
Start with the reference system
Differences in datum and projection create shifts that look trivial on screen but seriously affect area and boundary computation. Harmonising the coordinate reference is mandatory before any merge.
Metadata is not paperwork
Without a record of source, capture date and accuracy, a data layer loses its context and risks being used for purposes it was never fit for.
Appoint data custodians
Each data type should have a single accountable owner. That clarity prevents several versions of the same data all claiming to be official.