TT has wizards learning spells grouped by "colour" - basically, six arbitrary lists. So all wizards can do a bit of everything.
An alternative approach would be to group spells by type - a wizard would learn a certain number of ranks in "divinations" or "damage spells", which would function just like levels of Elemental Lore in TT at present; there would be a list of divination spells that a wizard could choose to learn or not.
This, I think, is probably a better approach from a gamist POV - it leads to more meaningful choice in character generation, and more differentiation between wizards - but it's not so flavourful, and it certainly doesn't fit TT's flavour.
However, you could easily superimpose a colour system on top of this, without too much additional work - you a have a list of spell types - in the TT context that list would probably run "illusions", "damage spells", "defensive buffs", "offensive buffs", "hinderances", "divinations", and "metamagic".
A level of "lore" in the more useful schools might cost more XP than a level of lore in the less useful ones.
Within each school there would be a list of spells, and for each spell there would be a list of levels it would be available at in each colour.
So, for example, "Halt 30" might come with the list "Green 3, Brown 3, White 4, Black 4, Grey 5" or whatever (almost certainly not those actual levels, of course) in the "Hinderances" list. "Quad Through" would come with the list e.g. "blue 5, red 7", and the note that you add the spell's colour to the damage call; some effects would be in only one colour, but we could afford more "coloiur bleed" than we currently can without all wizards becoming the same, because there would be so little "school bleed".
Instead of elemental skill and elemental lore, a wizard would buy "school lore" and "elemental lore"; you'd need both at a relevant level to learn a given skill.
Choosing to limit yourself to just one school would obviously be much more limiting than choosing to limit yourself to just one colour.
What do people think?
--Jacob