I have an 11-year-old quarter horse mare. She is very calm and easy going - great in the field, on trails, and other environments outside the arena. So, the barn she lives at is on a quiet dirt/gravel road. Cars do drive on it frequently, if that gives you an idea of the terrain. There is a horse at my barn learning to pull a sulky. Which got me into learning more about it for my horse as a riding alternative. I'm totally new at this, and don't plan to do anything without instruction - just starting research. Any tips on training? Best harnesses/gear suggestions? What would be a good kind of cart? Any suggestions are appreciated!