While I'm not currently at liberty to discuss the specifics a start-up I'm involved with, Social Fortress[1], is working with several human rights organizations to implement aspects of our technology for the purpose of allowing individuals to communicate privately, using open communication channels, without having to fear that their government can see / access the content of those communications.

To answer your question directly:

Find a problem that affects people of all 'levels' of society and do your best everyday to solve for it.

[1] https://www.socialfortress.com - The site is sparse on technical information but expect that to change in the coming weeks. Any specific questions can be directed to feedback@socialfortress.com