I agree with Leslie-start as mild as you can. I use loose ring snaffles on my OTTB and my QH pony who came to us having been ridden in a Tom Thumb. Wow-did he ever hate that bit and was just naughty. Unfortunately, it took me a while to think about changing his bit but when I did and put him in a loose ring snaffle (after being told by some heavy handed cowgirl to put him in a correction; so glad I didn’t listen to her!) he is now a different boy. Willing, soft, responsive and seems happy now! I feel bad I didn’t try the snaffle right away, but now I know. He is being ridden English now and learning to jump.