Hi, Kim! All of my pin trading knowledge and experience has come from my children and a wonderful group of people at
http://www.cjdpt.com/ - a pin trading group in my home state of New Jersey. I've gotten some great information from them on trading and etiquette.
I think it's perfectly fine to wear the pins you love and don't want to trade, but I might suggest one of two things. If you can, wear a separate lanyard featuring the pins you want to keep, and when you encounter someone with whom you want to negotiate a trade, you can put forward only the lanyard with the pins you are trading, and maybe say something like, "These are available to trade." Another thing you could do is put the ones you want to trade on one side of your lanyard, and the ones you don't want to trade on the other, and again, you could say something like, "The ones on the left I can trade." Both of those options allow you to show off your special pins without risking hurting someone's feelings by refusing to trade with them.
Have a great time pin trading!