I think that Wizard should be treated as an academic title, on the same level as Doctor, including a standardized abbreviation - "Wz. Ian McKellan" - that sort of thing.
To that end, I am formally founding the Universitatus Esoterica, a very reputable for-profit online university and diploma mill... but for wizards, witches, warlocks, mages, and the like. (No sorcerers though, those self-taught hacks can go fuck themselves)