New Jersey trainer Doug Payne has a low-key system for getting youngsters going confidently and calmly.
Be clear about what you actually want from your horse. Don't create confusing "noise," such as an unsteady leg. If the leg doesn't get a response, use the whip as reinforcement. Then, go back to the leg and see if it works next time.
Most problems with horses result when they feel confined, which results in the instinctual "fight or flight" responses. Many students tighten the reins to create a connection and add leg only when the horse slows down, but the connection should be made through the leg first at all times. Reducing the sense of confinement reduces the degree of the problem.
Generally when a horse bucks after a jump or when he begins to canter in an open field, he is doing it because he feels good, not because he is being naughty. Your best response to this action is to push your horse forward with your legs, not to punish him with the whip. Let him enjoy his job, it will make yours much easier.
When your horse performs an action correctly, reward him by softening the reins. Let him walk. Give him a pat. Let him know he did a good job.
Read more about Doug, the problem horses he has turned around, and his family background in horse sports in "The Go-To Guy for Problem Horses" in the May 2007 issue of Practical Horseman magazine.