Fiat money may not be created by a private group: Many learned scholars have condemned the entire idea of fiat (paper) money as unrealistic. Indeed, they have history on their side in that it has never succeeded for very long. However, paper money is simply a much more practical physical currency than anything else for a swelling population. Therefore, it will likely have to be part of the mix in the future of money.
There shall be no monopoly on currency: Even if the government is the only entity capable of creating fiat currency, no law shall be passed to outlaw any other form of currency. Currently, in America, legal tender laws force everyone to use private Federal Reserve Notes as money, and they enforce it with the guns of the State to prevent any competition from the likes of gold and silver or anything else.
Money shall not be created with debt attached to it: Currently, money is created out of thin air by the Fed, given to the cartel of private banks at nearly zero interest who then buy Treasury bonds to fund government spending. The bonds pay a much higher interest rate than the money that was created, and the payments for the right to use the nation's currency is paid for by taxes to the private bankers who create and provide no value to the actual economy.
Loans shall be made by full reserves only: Under the current fractional reserve system, new money is created every time a loan is made because the banks are allowed to lend what they don't have, at interest. What a scheme! In a new system, loans can be made by anyone at interest rates they determine (or the market determines) as long as they have "full reserves" to lend. In other words, if a wealthy individual wants his money to work for him, he may lend it out at interest. Or, as the current banking structure permits, several depositors can buy CDs at their local credit union who will then lend the funds to qualified borrowers. The system won't change much in this regard, except that banks must have full reserves to make loans -- not a fraction of what they lend, which creates new money with debt attached to it.
Taxes must be voluntary: I fully understand that this concept is so foreign to modern society that many will denounce it as impossible. However, it is absolutely essential for any of the above to work.