So you are looking to go from occasional gold maker to big time seller with a major footprint on your server? Well look no further than TradeSkillMaster or TSM as it is commonly referred to. TSM is a modular collection of addons used by many of the richest members of the WOW community to run their operation.
TSM and all of it's modules can be found here.
My plan was to do a few in depth posts looking at how to set up TSM as well as some of the more advanced tips I have learned through using it, but Faid over at Clockworkriot.com has produced a few videos that do a pretty good job of teaching you what you need to know to get started with your gold making empire.
Her videos can be found here.
Hope this helps those of you who aren't familiar with TSM. If you have any questions fell free to leave me a comment and look for more addon updates and guides in the future.