Successfully complete all the Mage Guild Recommendation Quests to gain 
access to Arcane University.
Then, create a Fortify Skill 100 spell that lasts for a few seconds on-self 
for Mercantile and/or Armorer.
With the Mercantile spell, cast it in front of a merchant, activate them, 
and you will be able to invest 500
gold at their store without being a Master in Mercantile. In addition, you 
can drive harder bargains. For
Armorer, cast the spell and then equip an Armorer's Hammer. Your hammer can 
be used infinitely
without being a Master Armorer. You cannot, however, repair magical items 
without having legitimately
reached the Journeyman Armorer level. Similar spells can be created for 
other attributes and/or skills:
Personality and Speechcraft for raising people's dispositions, Security for 
picking any lock, etc.