There are several ways to trade. First with Disney cast members, second with other pin traders.
If you go to a Disney Park there are will be cast member wearing lanyards. If the lanyard is back it means that anyone is welcome to trade as long as the pin you are trading for is not already on the cast member’s lanyard. If the lanyard is a teal blue it is for kids 12 and under.
When trading with other pin traders there are no rules that are set in stone. Some things to remember when trading, you can always say no. If the trade makes you feel uncomfortable or unsure walk away. There are always more people to trade with.
For information on what a pin is worth there are several good places to find an estimated value of a pin. One is pinpics.com an online resource were most Disney pins are list. It is easy to search and you can even keep track of your collection on line with their system. The second way is Tomart’s Guide to Disney Pin Trading. It is available to purchase at most online bookstore and at selected locations inside the parks.