Quote from dousie3. Make only clan members and friends who were your friend when you got the item (from a drop) people you can trade with (makes it so random people can't trade).
This I really like. Makes more clans interactive with each other, because how many times have you been in a guild/clan where nobody says anything?. Think this will help people communicate more. And trade with friends is pretty self explanatory. But this could also create the problem that you need to add allot of people that you don't know just to trade with them.