Consistency, two steps forward one step back, so once you’ve increased the difficulty of an exercise, always go back and make sure the basics are still perfect. Lots and lots of ground work is always helpful.
Just start how you would with a young horse and work on the ground as well as then the horse will trust you more and might be more willing to learn the things your teaching him just imaging yourself moving from one sport to another and how you would begin with that new sport yourself!
Hope this helps
Start right at the basics and be patient without expecting too much straight away, I find that they also work 10x better if they have a good relationship with their rider
Start with basics and bonding. Liberty work and natrual horsemenship is perfect for that!