Obviously you should have to own property.
Higher percentage of the public owns property than votes currently.
Would be neat from a sociological experiment perspective (akin to East and West Germany) to see how several States doing this would affect legislation.
I always like Bastiat's take on this in The Law:
"What I wish to observe is this, that this same controversy (in common with the greater part of political questions) which agitates, excites, and unsettles the nations, would lose almost all its importance if the law had always been what it ought to be.
In fact, if law were confined to causing all persons, all liberties, and all properties to be respected — if it were merely the organization of individual right and individual defense — if it were the obstacle, the check, the chastisement opposed to all oppression, to all plunder — is it likely that we should dispute much, as citizens, on the subject of the greater or less universality of suffrage? Is it likely that it would compromise that greatest of advantages, the public peace? Is it likely that the excluded classes would not quietly wait for their turn? Is it likely that the enfranchised classes would be very jealous of their privilege? And is it not clear, that the interest of all being one and the same, some would act without much inconvenience to the others?
But if the fatal principle should come to be introduced, that, under pretence of organization, regulation, protection, or encouragement, the law may take from one party in order to give to another, help itself to the wealth acquired by all the classes that it may increase that of one class, whether that of the agriculturists, the manufacturers, the ship owners, or artists and comedians; then certainly, in this case, there is no class which may not pretend, and with reason, to place its hand upon the law, which would not demand with fury its right of election and eligibility, and which would overturn society rather than not obtain it. Even beggars and vagabonds will prove to you that they have an incontestable title to it. They will say:
"We never buy wine, tobacco, or salt, without paying the tax, and a part of this tax is given by law in perquisites and gratuities to men who are richer than we are. Others make use of the law to create an artificial rise in the price of bread, meat, iron, or cloth. Since everybody traffics in law for his own profit, we should like to do the same. We should like to make it produce the right to assistance, which is the poor man's plunder. To effect this, we ought to be electors and legislators, that we may organize, on a large scale, alms for our own class, as you have organized, on a large scale, protection for yours. Don't tell us that you will take our cause upon yourselves, and throw to us 600,000 francs to keep us quiet, like giving us a bone to pick. We have other claims, and, at any rate, we wish to stipulate for ourselves, as other classes have stipulated for themselves!"
How is this argument to be answered? Yes, as long as it is admitted that the law may be diverted from its true mission, that it may violate property instead of securing it, everybody will be wanting to manufacture law, either to defend himself against plunder, or to organize it for his own profit. The political question will always be prejudicial, predominant, and absorbing; in a word, there will be fighting around the door of the Legislative Palace. The struggle will be no less furious within it. To be convinced of this, it is hardly necessary to look at what passes in the Chambers in France and in England; it is enough to know how the question stands."