One of the best WhatsApp security tips is to protect the app with a password or PIN. WhatsApp itself doesn’t offer such a function, but there are third-party apps that do.
Hide 'last seen' timestamp
Not sure you want people to know when you’re coming on and offline?You can disable or restrict who sees your ‘last seen’ time in WhatsApp’s ‘Profile’; ‘Privacy’ menu, in Android, IOS, Windows or Blackberry. Be aware though, if you turn it off, you won’t be able to see other users’ ‘last seen’ times either.
Watch out for scams
Anything offering a free subscription, claiming to be from WhatsApp or encouraging you to follow links in order to safeguard your account is definitely a scam and not to be trusted.
Whatsapp doesn't secure your data
Whatsapp is now working on securing your data but this will take some time and until then you need to be that extra bit cautious about your phone. This server has very little security and hence can be hacked very easily.