perhaps, something along these headings .....
Agriculture and Industry
Animals and Nature
Architecture and Buildings
Arts
Business and Law
Earth and Environment
Economy and Finance
Education
Electronics and Engineering
Film and Animation
Food and Drink
General
General technical and industrial
Government and organisations
Health and Medicine
History and Culture
Hobbies and Crafts
Language and Literature
Legal
Management
Mathematics and statistics
Meteorology and astronomy
Military and Defence
Music and Sound
People and society
Sciences
Sport and Leisure
Technical and IT
Travel and Transportation