Wow, sounds like you've got a good boy! If you'd like to continue riding bitless, you might consider getting a hackamore or side pulls. Since it's what he's used to I would recommend it. Personally, just playing around in a field is fine, but I don't know that riding on trails is a great idea w/a halter and lead unless he's VERY good. I would say just start him out in a pasture/round pen to keep him in a secure situation just to be safe at first. I don't know what you've done w/him, so I'll just tell you what I do w/a new horse when I'm not sure how they've been trained. Do you know if he has had much groundwork? It's always a good way to see what they know. Make sure you can mount w/out him going to the side and moving all around. Once you're on him, just ask for a walk, and don't just go in circles make figure 8's, serpentines, etc... Make sure he stops well too, that's important! If he does well w/that, ask for a trot. Just for a few paces and then bring him back to a walk. Do a lot of transitions to make sure he understands what cues mean what. Does he back? If he does well w/all of this, just keep slowly increasing what you ask of him and see what he does. I probably wouldn't ask for a canter the first time or two that you ride, you'll still be getting used to each other, but once you feel confident in his abilities and he trusts you have at it! If he shows confusion at something, he probably just doesn't know how to do it. Have you ever done any training at all? I assume you have a saddle to fit him? I bet you'll need a heck of a step stool to get on him!lol. Where do you do most of your riding?(trail, arena, pasture)