Evaluating Intelligence
Each cast of either a Magery or Mysticism spell has a chance to gain. Training one of these magic skills to the desired level while having Evaluating Intelligence raise passively is the preferred method. Once Magery or Mysticism is done training, repeatedly casting Magic Arrow is the most effective means. Wear a suit with 40% Lower Mana Cost and as much Mana Regeneration as you can. Weaken on yourself is a good choice if you want to raise also Resisting Spells.
Akira suggests Reactive Armor spell, it does not require a target, same mana as magic arrow. Once you finish training just be sure to turn it off if you wish. I typically work magery all the way up before I work this skill since you will gain this skill while working magery.
Mal suggests running a simple macro, via uosteam or razor, to cast feeblemind on yourself. This will raise Evaluating Intelligence and Resist Spells very quickly.