Use distinct sign-in credentials
Reusing a password ties otherwise separate accounts together. Choose unique passwords and use multifactor authentication where available. Keep recovery information current so you are not depending on a lost device.
Slow down unusual requests
Unexpected requests for codes, payments or urgent login actions deserve an independent check. Open the service yourself rather than allowing the message to choose your destination.
Review what you share
Look at profile visibility, old public posts and applications connected to your accounts. Change what no longer serves a purpose. Keep a note of the changes so the next review is quick and focused.