Begin early with young horses teaching them to pick up their hooves get them use to holding them up. Older horses might need to get a refresher course from a professional trainer for your safety and the safety of your farrier. The Farrier's job is to shoe or trim your horse not to train or teach your horse manners. The fact of the matter is, that we as horse owners often train problems into our horses. We don't always nip a negative behavior in the bud.
Horses are very much like young children.
The consequences of negative behavior is taught by establishing boundaries and providing displine. It is our responsibility to ensure that our horse knows how to behave when the farrier arrives. He does not have an easy job and the less stress on him will ensure a good working relationship with both you and your horse. Provide a clean dry work place for your farrier. A safe place to tie the horse and shade in the summer is a big plus.