Whether you're cleaning up an existing Lexicon or starting to organize terms from scratch, you must decide or determine two controlling factors:

1. What broadest categories will govern term organization - Concepts
2. What rules of grammar will control data entry and searches - Grammatical Form

Term concepts that organize the broadest vocabulary levels might include include:
Things - (Object Names)
Materials
Processes (or Techniques)
Events
Properties (or Attributes)
People (Maker/Artist, Designer, Significant Association, etc.)
Localities (or Places)