It's going to get tougher and tougher to make the real, deep, across the board cuts in the Federal Government and the various welfare/warfare state programs as, besides 45% not paying Federal Income taxes, those same folks are on some kind of government assistance.
Merge all welfare into a single monthly cash dole (fire about 90% of that bureaucracy), eliminate the overhead costs that eat up about half the "welfare" budget. Make it very clear to the remaining bureaucrats that "justifying budget increases by spending more" is not happening any longer. This step alone would save many billions annually. If states (like NY) think the monthly amount is too little ("our state costs more, wah!") then let the state chip in. No more Obama Phones, no more section 8, no more SNAP - make it a cash payment. No need to spend money and hire bureaucracies to control or monitor what they do with it.
Come back next month, because you aren't getting any more until then. (Make the receivers learn to budget by treating them like adults)
That is also the thing, make them actually show up to get the cash. They did this with ration cards back in the depression-war era, people showed up in person with their kids to prove they existed.
Eliminate the unnecessary federal departments like education, energy etc. Take non-military-related spending out of the defense budget. End all corporate and farm subsidies. Cut foreign aid down to immediate emergencies and allies only. Cut spending on the UN and all those related orgs. Stop funding NGO's.
Eliminate AmeriCorps, SeniorCorps, USA Freedom Corps (if it still around), Corporation for National and Community Service ($1 billion a year to promote volunteering, insane), White House Office of Faith-Based and Neighborhood Partnerships and all of these little "billion here, billion there" pet projects that build-up over time.