I have gone the path of successively imposing more and more rules on myself.

1st Edition:
No special characters (except useless ones like Mustado, Rafa and Malak, but I often don't take them anyways)

2nd Edition:
No Calculators

3rd Edition:
Only buy-able items. I did recant on this and allow Knights to use knight swords. The class is weak in comparison to the other classes, and gets totally hosed on the choice of end game buy-able equipment. I feel this balances things out, even if the Knight swords are a little bit OP in Ramza's hands.

4th Edition:
No raising brave, no using blade-grasp except on Samurai, no attacking unarmed except for monks

Future 5th Edition:
No Holy, no ninjas (though I do try to limit my party to one), no draw out on useful mage classes. Possible additions.