At npc training level, cast Protection until you can cast Bless. Then cast Bless until you can cast Magic Reflection. You can stay with Magic Reflection nearly all the way to GM, by using a Staff of Power (spellchannelling -15 mage weapon) at around 70 skill level, then using a series of wands or spellchannelling weapons (-20 thru -29) to the high 90's, at which point keep the -29 wand and switch to the Invisibility spell.

If you do your gaining in the blackrock area, you can GM magery in a single day.