Agreed with all said here.
ENJOY it, that's part of why we're doing it. Bring treats and have them readily in your pocket.
BE SMART, don't let the dog people make decisions for you. (I have had to cancel or postpone in the past, I always tell them ahead of time if there's a chance, so that it doesn't surprise them)
HAVE FUN! Again, enjoy the dog's company.
TAKE PICTURES. Plenty. The more dogs you fly, the easier it is to forget the previous ones. I have a few dozen dogs in my cubicle to keep me company.
T-SHIRT from PnP makes you easily identifiable to ground volunteers. If you haven't received one yet, request it. (they are bright red now, Christ - and they are free)
Crates work fine but most dogs behave and sleep in the back seat. Bring a "wrangler", aka "copilot".
If you can, bring a student pilot friend to:
- get them out of the traffic pattern for a change
- show them how real world aviation works after training
- introduce them to real cross-country flights
- expose them to PnP and suggest that they CAN fly pups as student pilots
FWIW, FBOs normally wave "landing" fees, parking fees, "service" fees or other means of extortion if you mention a charity flight. A nice FBO CSR might even discount fuel if you ask very nicely and let her pet the pup. We've had some pretty girls fawn all over some dogs, it is always awesome when the pup draws people love.
Again, HAVE FUN! And post pictures after. Or else.