Government should be by contract only. The citizen and the state should come to a mutual, official, legal agreement. All adults, upon turning 18 or 21 or so, should sign a formal, written, binding, social compact in which they agree to abide by the constitution and the laws of a given country in exchange for government services. This means in exchange for the defense of their liberty and the protection of their rights.
This essentially means the systematic, careful, full-time safeguarding of their person and property by professionally trained and armed government agents or civil servants. The would-be citizen or resident should freely agree to pay a certain fee -- say 3% per year of his local income or .5% per year of his local net worth -- in trade for expert police and military defense, plus court and jail services, plus the government administration thereof.
In theory the contractee of the state might be commanded to surrender some of his rights -- such as serving one year of military duty, or a lifetime of no slander or defamation in speech, or being subjected to subpoena coercion at any time. But the potential citizen or resident is always perfectly free to quit, or to refuse to join, such a slightly despotic state.
It's understood that at any time, for any reason, the citizen is free to immediately, unilaterally cancel his contractual agreement by giving brief, official, public or written notice. Thus he renounces his citizenship -- and consequent legal obedience and political loyalty -- to his former country and government. It's also understood that the government can strip him of his citizenship or political rights -- also by providing official, public notification slightly in advance -- for major violations of the constitution or law.
In both cases the person involved can either join another government or become a temporarily or permanently stateless person. But no fines, jail terms, or other civil penalties are allowed due to his "treason," especially not any property or wealth confiscation. If the former citizen owns land, and so chooses, he can theoretically become a one-man country. Or the previously-signed government contract may require him to sell his land for a fair price and then leave.
Because the former citizen or resident is no longer bound under political contract to some social group, and thus is no longer paying his service fees or "taxes", the old government will now stay off his private real estate, and will no longer necessarily protect his person or property from criminals and invaders, i.e. from any attackers or rights-violators. He must defend himself.
Moreover the newly independent person can no longer visit his former country without government permission, such as a visa of some kind. When such a person does visit he must temporarily subject himself to the local laws of the foreign government, and perhaps also pay some sort of visitor's fee.
Government by contract ensures that any given state is fully legitimate and proper in that it clearly and openly enjoys 100% of the consent of the governed, from its voluntary members. Convicted criminals may dispute this, but they freely chose to become citizens or residents prior to conviction. Their arrest, trial, and punishment should be entirely open, and a matter of public record, as well as completely based upon the principles of justice and individual rights, and a product of laws that the convicted criminal previously freely agreed to.
Without a formal, serious, contractual assent from the totality of its adult citizenry, and all free, sovereign individuals therein, any given government is not legitimate or proper, but instead a type of criminal syndicate or imposed tyranny which desperately needs to be avoided or obliterated.