Phil,
Just to add to the other great tips already provided....
You should try to get a lanyard and as many trader pins before you arrive...If you're lucky your local DS might have a few Americana Mickey pins still in stock..which are cheaper than park pins.
After you arrive in Orlando you might want to check out the Outlet stores...sometimes they have discounted pins that make great traders with cast members.
You should also check out DizPins.com (the news section), there you should be able to figure out what new pins are being released while you are there...It's very hard to find new released pins for trade on lanyards or books.
Your best bets for New Releases are Pin Central locations...like EPCOT and Disney's Pin Traders at the Downtown Disney Marketplace.
Now, once at the BWV's...there is a pin cart on the boardwalk in which the cast member has a pin book that you can look through and make trades...We stayed at the BWV last Oct and looked at the book every time we passed the pin cart!
Most pin carts have a book or two of pins....you just have to ask to look at them...We have found some great pins in those pin cart books !!!
Try to wear the lanyards whenever you're in public because you never know when you might find a good pin trade...or keep them in a camera bag etc.
Before we leave the room each time...we load up our lanyards with the pins we are willing to trade...and when we arrive back we decide which are keepers and which are going back onto the lanyards when we depart again.
We never take our pin books to the parks...it's a hassle to carry them around...plus we only put the pins we want to keep in books and don't plan on trading them anyways...an except to this is if you are going to a Pin Trading Event.
Last and most important!!!
Study the rules for pin trading and common courtesies...It will make pin trading a much better hobby for all involved!
http://disney.go.com/eventservices/howtopintrade.pdf
HAVE FUN!!!