Open WhatsApp
Tap Settings
Tap Privacy
Tap Last Seen & Online
Set Last Seen to Nobody or My Contacts
Set Who can see when I’m online to Same as last seen
Turn off Read Receipts if desired
Disable Live Location if enabled
Turn off WhatsApp activity indicators where available
Use Airplane Mode before opening WhatsApp to read messages offline
Close WhatsApp completely after use
Avoid sending messages while you want to appear offline