Most of the data models come from different groups of people interested in the creation of standards in an agile way.
Here you can access a cheat sheet (Let’s call it methodology) on how to tackle these tasks.
summarized these are the steps. It takes for granted that the group is already available.
Step 0. Gather documentation
Step 1. Compile elements.
Step 2. Meet to reach a Generalization proposal
Step 3. Internal validation
Step 4. Create the technical documentation of a data model
Step 5. Submit your data model
Step 6. Review
Step 7. Disseminate