A good place to start is repealing the disaster that is the Patriot Act.
However, a proposal before Congress right now would limit the scope of the NSA’s information gathering.
The amendment [pdf] basically defunds the NSA’s dragnet collection of every bit of metadata on all phone records as well as other bulk records that have not yet been revealed. The amendment still would allow the NSA to collect information under the original intent—and understanding—of the law, that is information actually related to actual investigations.
Of course NSA supporters are pushing back, including, unfortunately, the Obama administration. Like too many people in positions of power, the administration and the President seem to in the grip of fear about terrorism and have convinced themselves that any means necessary to keep us “safe” (what that means) are acceptable. They are mistaken. Such an attitude only feeds a creeping tendency toward authoritarianism in our culture, one which seems to be growing stronger because too few people in elected office see it as a threat. We see it in the militarization of police forces, in spying on Americans, in the absurd theatre that is the TSA striptease in airports. It is fueled by fear and it fuels fear. I believe it is dangerous.