Wizards might vary from region to region, but this would be the concept that each Wizard (or at least most) belong to a certain wizarding tradition. Each Tradition knows 2-3 schools of magic and has a strong theme. For example:
The Dark Order of <god of undeath and destruction's name>
Schools: Evocation (Preferring flame), Necromancy and Illusion (Shadow spells only)
Northern College of the Mirage
Schools: Illusion, Abjuration and Conjuration (Creation subschool only)
Under this system there would be a certain archetype for the pathfinder wizard to fit.
Each tradition would likely have 2 good sized schools and a smaller school, or a subschool with it. As well as typical themes that would fit in the setting.
Actual organizations and archetype to be thought of later.
This may only apply to wizards from a particular continent or country too. Individual organizations will be listed under organizations.