No matter the gait, when the horse is soft in the mouth, you have to continue to push forward to retain that softness.
When warming up the horse, keep the hands wide. Tension should only appear in the rider's shoulders, never in the hands or elbows. The elbows only block and serve to create tension in the horse's mouth.
When needing to bring the horse's head to the inside to create throughness and make the horse take up contact better on the outside rein, bring the inside hand to the inside hip. This causes any positive tension in the rider's arm to remain in the shoulder, rather than allow negative tension to remain in the elbow or fingers. The fingers, especially the fingers on the curb rein, should always remain loose.
Always ride as if you have on hand on both reins. If you get stuck, put both reins in one hand. This serves 2 purposes - to see if the problem is your lack of coordination in holding both reins with both hands or if the problem is some sort of tension in the horse (excitement, etc) and, because the horse always responds better when you ride with one hand, it aids in developing and maintaining throughness in the horse. At the same time, bend the horse inside with the outside leg to establish and maintain throughness. You may have to use the outside leg twice per stride. Yes, kicking twice per stride isn't very easy. Deal with it.
No matter what you do, always focus on the quality of the gait. This is said so much as to render it almost trite, but it's the best advice out there, because the rest gets easier after you've accomplished it.
Never make pancakes when typing up a horse training blog.
