Theres probably threads about this...

[Dulu]

Max into Int.

The rest.. doesn't really matter. Stamina is probably the best min/max number-cruncher answer.

Agility isn't awful for leveling those pesky defensive skills a little bit faster..

I also play a caster, High Elf Wizard (clearly not too concerned about min/max since I'm HIE, but I digress..) - and I put my remaining 5 into strength - just to help with carrying luggage around.. 5 pounds is a lot.