My advice is to just have fun with it and don't take anything too seriously. You will end up with scrappers when you're trading with cast members, it's unavoidable. I keep my favorite pins in a pin bag or on the lanyard. I have some cheaper (real, not scrapper pins) pins that I will use to trade. That way, if I end up with something not 100% legitimate, it doesn't bother me.
I agree with Jessica527...locking pin backs are your friend. I once lost a favorite Pirates pin...never again!
Have a wonderful trip!