This is the advice of the former head of social media in President Jacob Zuma's private office.

The advice by master's student Sunil Gopal was given as the American Consumer Report last week revealed that most Facebook users worldwide were sharing too much information and simply ignored privacy settings.

Gopal said the recent Twitter storm over racist tweets by model Jessica dos Santos was an example of how private thoughts could easily be exposed to the public.

"Many people are unaware that other members of the public can easily view their comments and profile information. They are under the impression that only their friends and followers can see their thoughts, feelings and actions.

"However, literally thousands of others are now privy to one's personal information, from where you are and what you're doing, to being able to view your holiday pictures.

"With the introduction of the timeline facility on Facebook, it is possible that thousands of others can see your views and pictures connected only by a common friend," he said.

Two weeks ago, Dos Santos tweeted to 2591 followers: "Just, well took on an arrogant and disrespectful k****r inside Spar. Should have punched him."

Her racist post was re-tweeted with thousands retaliating, including Tshidi Thamane, who called for all whites to be killed.

Gopal said South Africans were sharing too much information on social networking sites because they were unaware of the implications.

"Employers and potential employers also pick up information on social networks so one needs to be circumspect about online posts.

"Drunken pictures and tweets from last year's Christmas party are a no-no. Social networks sometimes provide information about a person's character that interviewers are not able to pick up.

"People have been fired for posting negative comments about their company or bosses, or even comments that are deemed racist," he said.

Gopal said South Africans were generally unaware of the privacy settings for restricting information to friends and followers.

"South Africans need to take steps to restrict their privacy settings on social networks so that only those they want to are able to see their information.

"Open profiles on Facebook allow anyone to see all your information.

"It is also possible to restrict who views what on your Facebook profile by listing people as close friends or acquaintances. More important, do not accept friend requests from anyone and everyone."

The American Consumer Report also found that Facebook users exposed themselves to burglaries by using the check-in facility, which told criminals that they were not at home.