There is no one correct methodology for developing ontologies, nor is there a single correct result. Developing an ontology is usually an iterative process. You start with a rough first pass at the ontology. You then revise and refine the evolving ontology and fill in the details.
In practical terms, developing an ontology includes:
- defining classes in the ontology
- arranging the classes in a subclass-superclass hierarchy
- defining slots and describing allowed values for these slots
- filling in the values for slots for instances