Make sure your horse is safe to work on. If your horse has a problem with farriers, let your farrier know and work to solve the problem. If he pulls back, make sure there is someone to hold the horse for the farrier. If he can't work, he doesn't eat. Greedy pooches trying to steal a tidbit of hoof out of the farrier's nippers can get a farrier hurt and the dog killed.
Rambunctious children can get themselves and the farrier hurt as well.
Pay your farrier bill on time. If you are there for the appointment, make sure your check book is too. If your farrier bills you, pay it within 30 days, or better yet, as soon as it arrives. Pay with a good check. Don't complain about the cost of farriery.