What should I upgrade? (Gear List Included: 48 Mage)

[guineapig]

THis largely depends on what you plan on doing with your mage. You mention BD resist gear. If you plan on raiding then yes you will want a set of resist gear but that's not something you need to be wearing full time.

Honestly mages are one of the least gear dependent classes in classic. If you are chain casting pets and medding the rest of the time the size of your mana pool really isn't going to make difference.

I would say that if you are happy with your mana pool than looking for things that start raising your hitpoints without reducing your mana pool. IE: black sapphire pieces.

If I were you I would just try to get some raid pieces in Hate and Sky then wait till Kunark. There is really nothing you shoudl be wasting your money on before then.