My barn is holding its "real" show in RI! We are all very excited!
Bring all of the stuff that you would to a normal show and the follow (plus more ). Okay, I would prepare the food in little baggies so that you just have to dump them in the bucket. If you are going with a big(erish) barn then you will probably bring bags of differnt foods. I would suggest bringing enough buckets as we always seem to be short one. Also, bring enough double ended snaps because not all shows have special ties in the makeshift stalls! We always forget that! :) Find out ahead of time if they barn has on sight hay and shavings that you can buy (they probably will). As for tack, I always bring extra of everything to be safe. Make sure you bring schooling tack and a square pad for when you don't want to dirty your show pad. I have, overtime, created an "emergency" kit that I bring to all shows. It has bandages, aspirin, scissors, chapstick, suntan lotion, rags, baseball hats, stick notes, markers, a sewing kit - a little bit of everything! I keep adding to it too! I would bring an ace bandage for your horse's tai when it braided, and a seam ripper to get braids out.
That's all that I have now but I know i'll think of more!