I think everyone will agree that America is pretty broken right now. I'm not just talking about the toxic political atmosphere either, but that's preventing solutions from being created. Excessive polarity of partisanship and winner takes all politics are a direct result of the election laws are rigged to favor a two candidate race. So there needs some fixing there, in the election laws, both in how we vote (like winner take all rather than approval voting or other schemes), and who we allow on the ballot (barriers to entry against third party and independent candidates disenfranchises more than 60% of the voting eligible public).
As for policies, first we need to list what are the important problems.
Firstly, the fiscal sustainability of the nation is in my opinion the greatest problem. We are verging on $20 trillion dollars after eight years of the most spendthrift president in US history, racking up nearly $12 trillion in debt in the same time it took his predecessor to rack up a mere $5 trillion, which the current president had attacked his predecessor while a Senator as an excessive spender. Debt is now more than 100% of GDP, which has only happened twice in US history. This is fixable, but the old tired refrains of more taxes and more government will only hurt us more.
The biggest problem is entitlements spending, which everyone acts cannot be cut for any reason, which I say is bunk. Entitlements spending is ballooning for one reason only: because the average life expectancy continues to climb, while the retirement age remains static at 67 years. The average retiree only contributes 3.5 years worth of money to the system, but lives more than 12 years after retirement. This is obviously unsustainable. People are not able to invest their social security savings in the free market, so they aren't earning a sustainable rate of return that could ensure their retirement.
At the same time, Medicare is also ballooning for the same reason, while government employee pension costs are exploding for similar reasons.
The solution to each of these is obvious: increase the retirement age. I recommend increasing it 2-3 months each year, until it is 6 years less than the average life expectancy, and have it float thereafter as expectancy changes due to health care advances. If we go with 3 months a year, direct half the savings toward reducing the deficit, and expanding the space program. By indexing the retirement age to life expectancy on social security, medicare, and government employee pensions, we will restore federal and state governments to fiscal sustainability within a decade, easily.
As I noted in a previous article, we need to get serious about space exploration. We need to get serious about commercial exploitation of resources in space, colonization of places like the Moon and Mars, and exploration beyond our solar system, as well as preparing the capacity to defend the solar system now that we are realistically discovering phenomena in our nearby region of the galaxy that could potentially be alien species that are possibly at least as expansionist as we are. I would say that defense spending on Earth needs to decrease, and redirect some of the savings to an Earth Space Navy, with separate detachments funded and manned by the five major factions in the world today: the US (and its anglosphere allies), Russia, China, Europe, and the Nonaligned nations (including India, or Brazil).
Space is where the next big expansion of our economic pie will happen. Earth is a closed system, with finite resources. There are near infinite resources out in space. The best way, therefore, to expand the pie, to grow the wealth of every human, is to open our economy to the resource base beyond Earth, and this work should be done by private industry, ventures like SpaceX, Planetary Resources, among others.
Sectarian conflict: There is a big potential for outright global conflict brewing due to the aggressive expansionism of islamic based ideologies of a hegemonic caliphate. Both the shia population, centered in Iran, and the sunni population, with power centers in Saudi Arabia, Egypt, and Turkey, are all pushing to similar ways, with strong Hijra campaigns to mass immigrate un-assimilating muslims into Europe, and the US. This Hijra needs to be halted, and if muslims do not learn to assimilate and accept the Constitutions of the nations they immigrate to as law, they should not be allowed in.
Individual liberty: the source of all political power originates in the individual sapient person, a self owning, self determining moral agent with natural rights derived from their evolved self owning sapience. The only valid means for sapients to interact with each other, or as groups, is through voluntary exchange, not aggression. Trying to conglomerate more nations together into superstates is contrary to individual liberty. Recent events like Brexit indicate that self determination of individuals and the groups they voluntarily belong to is paramount. The post-Brexit economic boom in the UK indicates that this is the right choice for people to take.
Just as groups or nations are self determining, so to are individuals, since the power of any nation is only legitimate by delegation by its individual members to it of their own, original, power as sovereign individuals. There should be places in the world where individuals can live peacefully without mandatory participation in nation states, free to defend their own rights as they see fit. Countries are country clubs, but membership should not be mandatory, and nonmembers should be free to live where they don't have to be a member of any club, but at the same time cannot demand any benefits of membership if they aren't willing to pay for them.
Tolerance: Part of not aggressing is to tolerate the existence of others you don't agree with, or don't like, to not take their stuff, or oppress them from exercising their own rights. You don't get to use your disliking what they believe, what they have to say, or how they live their lives as a basis to oppress them just because you are offended by them. It doesn't matter what your politics or religion is. Mind. Your. Own. Damn. Business.