A few hundred years ago, Freedom of Religion was the idea of the hour. People moved across the ocean to try it out. Colonies were founded on it, countries wrote it into their founding documents. What has been the result? Where Freedom of Religion is respected, peace between the various religions is the norm, and violence the exception. The people thrive, and are happy.
A bit later, thinkers like Frédéric Bastiat agitated for Freedom of Trade. They argued that free trade not only ensures peace between people, but between nations as well: "When goods do not cross borders, soldiers will." What has been the result? Where Freedom of Trade is respected, the people flourish, and the nations are at peace. Where Freedom of Trade is not respected, the nations war, and the people starve.
So the time has come, I think, As de Molinari suggested, to seek Freedom of Government. Just as with religion and trade, monopolies should no longer be acceptable in government. Each person should be free to select for himself a government that best suits his needs, just as he may select a religion that best suits his needs, and like religion, each person should be free to have no government at all, or to start his own. Just as no person may choose another's religion for them, none may choose another's government. Just as with trade, no government should interfere with the operation of another government, nor prevent it from serving it's citizens. Just as with trade, each government should be free to provide it's citizens with whatever services it chooses.
What do I predict will be the result? With each previous Freedom, the people's lot has been improved greatly. No longer do we see catholic armies hunting down and murdering heretics. Cargo ships are now more numerous on the sea lanes than warships. When people are free to change governments as freely as they may change churches, I predict that war itself may become a thing of the past. For what purpose would war serve, in such a world? To gain citizens? No, they could simply change governments to another government. To gain resources? It would be cheaper, and more efficient, to gain them through trade, or by enticing the citizens which control those resources to switch. To gain territory? No, again, to gain territory, they need only entice citizens to switch. The only reason left, then, is personal vendetta or hatred, and "because I don't like you," has never been an acceptable reason for violence amongst civilized people.
That's not to say violence would disappear. This is no utopian dream. But it would, I believe, be greatly reduced. There certainly would be less reason for it. Some people would still seek to control others against their will. But these people would properly be seen as criminals, and treated as such.
How to get there from here? That's actually the simplest part. Imagine, if you will, an election. An election where everybody wins. Whoever you vote for, gets the office you voted for. The catch is, of course, that only people who voted for that person get the government with that person in it. Everybody else gets their own government, constituted however they want. For some people, who vote on issues, that might be a little confusing, but most voters stick to party lines, so that should be a minor problem. After a few of these elections, all the "borders," or at least the "platforms" of the various governments should be fairly well defined, and so people could then choose their government without an election, perhaps by filling out a few forms, and placing a sign in their yard.