In my opinion the most important skill we can teach a horse is to lead brilliantly. Partly this is because most of us spend more time leading our horses than any other single task. But even more importantly leading is one of the earliest training tasks that sets up our relationship with our horse.
Letting Horses Make Decisions
When I was first starting to learn about horses and horsemanship, my teachers all had rules that I was meant to follow. I was to mount from the left of the horse. I was to lead a horse from my right. I was to ask a horse to pick up its feet by pinching the chestnut. When there was a disagreement with a horse I was to always make sure I won. If a horse turned its tail towards me I had to always correct it. A horse should not be allowed to stop when it had a bathroom moment.