The Unassisted Path to Grey Magedom
I had been working out the path for a character who will become a Grey Mage in the course of their life, without assistance from a Chantry, and while it may be a long and arduous process, it is doable.
They would have to develop their Arcane Lore, and Arcane Discipline as well. along the way, as their Arcane Lore developed, they'd learn to invent spells of their first Convocation - starting in every Convocation with Feel, Focus, and Sanctum. Possibly Infuse, too, to strengthen a Convocational residue for analysis. As Arcane Lore develops, they would gradually grasp the principles behind the Secondary, Tertiary and Diametric Convocations, until the greatest leap of faith - somehow taking the step to Grey Magedom at ML 101+.
The task would be akin to capturing a bird in a bucket, but it could be done. The only hurdle is the Ritual of The Core - which would require the Disquisition named in HMG Shek-Pvar p. 36 to fall into their hands, or something else ... perhaps contact with an artwork of Earthmaster origin?
How would you develop your character into a Grey Mage? What different steps would you take?