Active
Activate the skill by macro or skill button and target a creature or player. If you don't get a gain, find a new target. If you do get a gain you can use that target and all proceeding ones again to try and gain.

Passive
Each cast of a Magery spell has a chance to gain. Training magery skill to the desired level while having Evaluate Intelligence raise passively is the preferred method. Once Magery is done training, repeatedly casting Reactive Armor is the most effective means. Wear a suit with 40% Lower Mana Cost and as much Mana Regeneration as you can. Such passive gains of Evaluate Intelligence can occur even when casting a magery spell fails (fizzles) and with magery spells which are not influenced by Evaluate Intelligence (for example Mind Blast). If the goal is to raise Resisting Spells while completing Evaluate Intelligence, then casting Weaken, Clumsy or Feeblemind on yourself are good choices, these will raise both skills. You may wish to set and lock your magery at 0 while training eval.