How to start riding my horse bareback?

You really don't have to prep him much. It might be a little interesting for him at first, but if he is sensible he should be quiet. When you want to hop on him bareback, have someone handy to hold him still. Make sure you have a helmet on in case he gets scared. Get a tall mounting block, and just slide on his back. Sit there for a few minutes and let him get used to your weight being concentrated on his back instead of being distributed by a saddle. Have your handler lead him around at a steady walk then boost up to a brisk walk. Once he's comfortable, try a slow trot. He should do just fine. Hope this helps!