The indoctrination of Americans into hating and fearing socialism hold back the masses and American thinking. In much of the developed world we embrace liberal socialism. In the USA sits the false memories of the witch hunts against soviet commmunism during 1940s-60s.
Perhaps a simple rebranding of the word socialism is required.

@Veteran229 Not accurate. As a veteran of both the Cold War and the Berlin Crisis, I know the facts to be different. We have always contributed to the defense or Europe, not out of the goodness of our national hear, but because we NEED European allies, and because in would make life for the USA very difficult if Russian had control over all of Europe. We have always wanted to face Russia in Europe, not at our own shores. Get it straight, fellow.

@Veteran229 Imagine the USA reduces it's military spending, and instead reinvests into social projects instead? The USA currently sees itself as the world police and like the British Empire once was, and feels it needs to spend so much as a matter national prestige.
The USA is free from the threat of invasion - Canandians are too nice and Mexico far too weak, even if they both got together to attack. So why else does the US need to spend so much - foreign investments needing to be protected, projection of power, internal investments. The world is a complex web of interactions.

@Bobby9 Lets go back to the original question then where defence expendature isn't part of the question.
Public spending on universal healthcare free at the point of need is in the public good, as is a retirment programme. In the UK we have a separate tax called National Insurance, which covers us for a small retirement pension (one of the smallest in Europe) and healtcare free at the point of need cradle to the grave. The pension was brought in by 1908 and the National Health Service in 1948. Countries such as Germany had brought in a NHS prior to WWII.
So, everything costs money and it must be paid for through central federal taxation. The USA with some 320+million people and with a large surface area it cannot be brought in overnight. It will need to be phased in and matched with the American social norms.
In America the term socailism is a scary word bringing up visions of Soviet inflitration and a state theft of private property for the public good - or rather the good of the Communist party leadership! There needs to be either a rebranding of the word - Publicism, Commonwealth, Commonism? But what socialism is, is the public good. The richer pay more so those who cannot afford can have the same universal benefits. If everyone follows the American dream and succeeds, then who sweeps the roads, looks after the infirm and flips the burgers? Society requires a viable working class to make it work. Not everyone is cut out to be a CEO and Walmart greeters still need to pay bills and enjoy life.
As for how to spread the word, take a look at what is working around the world and not only copy it, but improve on it.
Consider this wee tangent, my wife had a brain tumour, the NHS looked after her medical needs for around 25 years until it killed her. The medication and treatment costs of MRI/ CT scans, Chemotherapy, Radiotheraphy, surgery, hospital stays, a new car (returned after her death) and aftercare together with anti-epilepsy medications would have cost millions of pounds. Then I for about five years I had to stop work to care for her - paid for by the state. The state also contributed to her funeral costs, then put me on one year of retirement based on her state pension. During the final stages of her illness, we lived on fairly decent welfare benefits. Now I am back to work, putting back into the system which helped me. I work in healthcare, paid for by the state looking after the needs of those who cannot look after themselves independently. Without the efforts of people like me, other people die.