My ideal would be to have classless system, but i think that's been shot down, but this could be an alternative to it. Give each person a percentage that they could have in skills and/or spells and let them choose their own.
Another thought I had on spells was choosing "schools" and "cross-schools" if you will (those of you that know D&D magic prolly know what I'm talking about). Or in 4D, it would probably be elemental schools and cross-schools.
What I'm talking about is choosing your "school" and by doing so, your cross-school is chosen for you. Your "school" spells would be more powerful, but you wouldn't be able to learn anything in your cross-school spells. Or if we're talking the elementals the example would be, if you chose fire, you'd be able to cast fireball at more damage and other fire spells would be more effective, but nothing at all in the ice elemental school. Everything else would be normal.
Kvetch