What should I bring if I want to NPC the entire weekend.

Not sure anyone's mentioned this yet but you should probably bring some extra socks.

Generic clothing that fits into a medieval/fantasy setting. Yes, you can get by with black sweat suits, but having your own "peasant garb"is very useful for when you go to get breakfast or wander to your tent at night. Not having to go out of game during those walks is nice. plus it looks better to layer the costuming over a period outfit.

Everybody jokes about bringing enough socks, but I have found 2 pairs a day to be more than adequate; usually, after the first puddle and sock change you will be more careful.

Thermal layers are vitally important, so long johns, under armor, and even period sweaters are very useful for staying OOG warm but keeping an IG appearance. Bring a black knit hat and black gloves, you will appreciate them immensely once the temperature falls.

Bring some energy or clif bars to munch on; it is vital that you keep a high caloric intake or you will crash on Sunday like a bus full of nuns in a superman film.

You must bring a solid pair of boots; you will be far more uncomfortable than if you brought your hiking boots with you than a pair of sneakers. Take care of your feet and you will enjoy your time camping more than the poor fellow who didn't!

I can't disagree with the advice to bring a lot of socks, but I would suggest that if your socks are getting wet, your shoes are also probably getting wet. Thus, I would suggest you bring an extra pair of shoes (especially if the weather is poor).

I also like to have an entire set of dry clothes (including shoes) in my car as a back up. Whether backpacking, camping, or roleplaying, knowing you can change into a dry and warm kit when all is said and done gives you more options. If I knew I had to drive two hours soaking wet I might be more cautious about my actions prior to my departure -- dry clothes allow me to forget about the after-game repercussions.

Looking forward to seeing you IG.