Magic-users in Karameikos as a class are less common than the fighter, cleric and thief classes. Therefore, they are generally regarded with more scepticism and wonder than in other nations of the Known World. Wizards of higher level are very rare to be found in Karameikos, as they are often drawn to Glantri, the center of magic on the continent of Brun. Therefore, aspiring apprentices often have a hard time finding a master in Karameikos. However, though it may be rare, the wizard/apprentice relationship does exist in Karameikos.
Many Karameikan magic users get their arcane training by joining the Magician's Guild of Karameikos in Specularum. Admissions at Apprentice level are quite easy: anyone showing some talent (as judged by Grand Master Teldon) is allowed to stay and attempt to become a wizard. Teldon sometimes takes in poor urchins, but most apprentices are already 1st level wizards, who have acquired a minimum of magic education from a tutor in some small village or town.
When a candidate for the guild learns the cantrip skill (or spell) and Read Magic, the candidate is considered an Apprentice, and is supposed to work for the Guild, providing the due or one royal per month either in money or in equivalent services. When the Apprentice masters 2nd level magic, he or she is tested for understanding of the basics of magic (a test of Spellcraft), and then promoted to Journeyman level. Journeymen stay with the Guild for further training and spell, but mostly to exploit the laboratory and library of the Guild. As they advance, journeymen pay a higher fee.
A successful and inventive Journeyman, who provides a new spell to the Guild and shows ability to cast 3rd level magics becomes a Magician. He is supposed to research the spell personally, but some just learn the spell from other Schools or private tutors. A Magician is able to work on a permanent basis as advisor/court wizard or professional adventurer. Magicians are often invited to spend some time outside Karameikos either working for foreign governements or studying at the magic academies of Thyatis.
Masters and higher ranks are reserved for successful wizards, who have now taken on some apprentices of their own, or at least teach classes at the Guild. Since they already provide some service to the Guild through their teaching activity, they are exempted from paying a fee.
Since the Guild is very small, the upper levels are commonly lumped in the Master rank, and enjoy the same rights. The only exception is obviously the Grand Master. This position is supposed to be elective, but Teldon, as the founder and Grand Master for life, is already an exception.
As a general rule, the guild dues are low, but the members are expected to accept at least one mission for the Guild before passing to an upper rank, which allows the Guild to get some extra income. However, the low fees policy has not helped much the Guild, since it doesn't allow investments in better equipment or new books, let alone a new Guildhall--the current one is quite small, and it must also double as Teldon's personal tower.
Since, Karameikos is not very advanced when it comes to spellcraft, and therefore many higher-level spells are not commonly known. At a certain point, a magic-user character will no longer be able to learn from the common magical instructors of Karameikos; after that point, all new spells must be learned from scrolls and other adventurers met during journeys, or at the Glantrian Great School of Magic.
Congratulations, you have now successfully created a Mystaran character!
For further development of this character, consult your Dungeon Master.