Identify large categories first
Photos, videos, downloads, games and duplicate archives often matter more than tiny cache files.
Do not delete unknown system folders
Removing unfamiliar operating-system files can create a larger problem.
Move or archive deliberately
Files can be moved to external or cloud storage when a verified copy exists and the new location is understood.
Leave working space
A drive filled to its absolute maximum has less room for temporary operations and updates.
General consumer technology information only. Interfaces and menu names change. Before resets, reinstalls, storage changes or other major actions, verify that important data is backed up and use current manufacturer/service-provider instructions.