If you want experience running a gold selling business, you may first want to try running your own store on PlayerAuctions.
You'll have everything set up for you, Payments, fraud prevention, and access to buyers right away. Once you get a handle on how to operate deliveries, inventory, for sale offers, you'll have enough experience to open your own site, and will have learned a lot of valuable lessons in the process with the the risk of losing anything (since PA covers that)