Before starting a horse in Four-Reins, get a simple bar bit (not a snaffle) without shanks. This bit should not be stainless steel. I use one made from what we Peruvians call "sweet metal." Put it on a simple headstall without the reins about a month or six weeks before you intend starting the horse in Four-Reins training. Slather the bit with molasses and gently put it in the horse's mouth in the correct position - do this often. You can use it when you are riding the horse in bozal or while he stands tied, but as much as possible.
This simple procedure will aid your horse in accepting the bit better and faster when it is time to start the Four-Reins phase of training. When you start Four-Reins, change to a regular Peruvian bit, but continue to slather it with molasses. With this method, your horse will love the bit!
About two weeks before you anticipate finishing the 4 reins stage of training, change the heavy bozal reins for a pair of very light reins. Make all of your last corrections using these light weight reins. You do this so you are not pulling excessively on the bit. This will make sure your horse is ready for the bit alone.
When you are first breaking and riding a horse always walk the horse for the first 4 weeks to two months of training. Do circles, figures eights, backing, stops - everything you want to do with your horse - do at the walk. Your horse will learn faster, get used to the weight of the rider and will strengthen its ligaments and tendons with very little risk of injury.
If you are having a hard time sit stopping your horse, work him along a fence. Pull in the rein closest to the fence so the horse turns his face towards the fence and stop at the same time. The horse should stop with his rear leg closest to the fence, farther ahead than the other.
Repeat this exercise to both sides and when your horse does it correctly then start pulling both reins at the same time and have your horse stop with his two rear legs under his body. Do this exercise first at the walk, then faster and faster until you get to the speed you desire.
If your horse is very nervous and jumpy when you are working with him, give him more time at liberty. If you keep your horse in a stall or small paddock, put him out to play for 1 to 2 hours everyday. It is better to do this before you work him. This is more helpful during the winter. This time at liberty will help release some of his excess energy. Little by little you can decrease play time until the horse learns to release his energy while working.