Bring lots of small pieces of food, a clicker if you use one, a non silent toy or toy and any articles you may have like a glove or a sock. Bring a bed/mat for your dog to settle on in-between turns.
Part of this may class will be outside weather permitting so bring a coat in case you need it and wear sensible flat footwear.
Bring a drink if you want one. There will be a short ten minute break.