The most important thing is to find a good trainer who will give you constructive criticism and precious advice.
If your horse has a "cow sense" it will be easier, but a horse without cutting blood can be trained to have cow sense, as long as he's reasonably athletic and has adequate muscling.
You have to focus on these points: willingly and quickly stopping in response to your cues, backing readily when asked, backing smoothly in circles and rollbacks.
You have some great videos here: https://www.youtube.com/user/ltrocha
Hope it helps!