I have an obedient horse, what's next?
So I was hoping some people could help me out with this. I was thinking my POA might make a nice enough cart horse, just as like a hobby every once and a while. He is already fairly obedient. His groundwork is pretty much impeccable, and he listens very well most of the time except for when his personality gets in the way. (He likes to test people quite a bit and has a case of the nibbles.) He is alright with riding most of the time, fine with saddle and tack.
So I was wondering what is the first step you take? He listens pretty good to a bit, but still needs more work. (I usually don't even work with a bit, just a rope halter and some make-shift reins. My trainer has a bitless bridle that I ocassionally will use.)
I'm just sort of lost. I don't really have any harnesses yet, nor do I have a cart. (My dad and I are planning on building one that will fit my horse well. I'm fairly certain there wouldn't be a cart that would fit him perfectly unless it was custom made, which would cost a buttload if made by someone else. My dad has plenty of experience making things, no worries.) So I just need suggestions as to what I could practice to warm up for this.