Download the custom content or mod file from a trusted source
Check that the file is compatible with your version of The Sims 4
Open the downloaded file if it is compressed
Extract the contents if needed
Locate the Sims 4 Mods folder in Documents > Electronic Arts > The Sims 4 > Mods
Copy the custom content files into the Mods folder
Keep script mods and package files in the Mods folder
Do not place files deeper than one folder level if possible
Enable Custom Content and Mods in the game settings
Enable Script Mods Allowed if the content requires it
Restart the game after changing settings
Verify the content appears in the game’s mod list or content browser
Check for updates after game patches
Remove broken or outdated files if the game has issues
Back up your Mods folder regularly