Start by buying.
Seriously, this will give you an overview of what listings look like, various types of listings, and the customer experience.
It will also help you build feedback. Low or no feedback is a scammer magnet. Feedback is a measure of trust.
Before you start buying set up your Paypal account and back it with a credit card. This is make your payments instant, speeding up delivery and gives you an extra layer of Buyer Protection, although PP already has very good Buyer Protection.
Now go up to the Sell link at the top right of this page. Read all the pages on the drop down menus.
Come back with specific quesions.
