Have you ever traded a pin? You can get pins from honors or you can buy them it is your choice. You use your pins to put them on your sash. Some people will give a fair deal on the other hand some people will scam you.
If you are going to trade ask to touch and look at it and to touch it to make sure it is not broken look at it to make sure you like it. Think for a minute. Do you really want this pin? Is it worth it? Is it valuable? If not, do not do the trade!
Try to complete sets like that, you will get more pins. Try to give good pins but not too good pick ones that you will keep and trade.