Ignorance is your biggest threat.

The National Security Agency is funding research into harvesting information people post about themselves on social networks and online communities and could possibly combine these with other data to build extensive personal individual profiles.

BeyondPR

And ....

But there's an ethical dimension that needs to be considered in engineering radio-readable products. These products are potential privacy-bombs, capable of wreaking great havoc in our personal lives and the body-politic. They have the potential to be systems of control, rather than empowerment. As Mitch Kapor says, "Architecture is politics." The way we design these systems will effect the way we live our lives: in freedom or in tyranny.

Cory Doctorow in Bloing Boing

I have thought for some time that there is a market for tutoring others in how to become savvy in the ways of the web and how to protect your online persona.