When working with a horse that does not have a great natural lengthening, make sure that you don't ask for too much too soon. Compare this to a singer who is training their vocal cords… they gradually expand their vocal range until they hit their limit. This helps to prevent them from overextending themselves, and builds up confidence in their abilities.
A good halt is square because it was a good, balanced, well ridden halt. Not because the rider has taught the horse the "trick" of squaring up after an unbalanced halt.
The Dressage horse is supposed to be (and look like!) a "happy athlete". If the horse does not look happy in his work, that work is probably not correct.
"The horse's back is like a bridge that carries him and you, and the neck completes the bridge. All the energy created by going forward from the hindquarters to the bridle makes your horse's back strong and develops those muscles that create the bridge. Without energy through the neck, the bridge is out and you can't do anything." ~ Jennifer Baumert
"If you aren't sure [when jumping], ride forward, because being under paced is not only harder for the horse, it can make the fences dangerous at the higher levels... Fences are made to be taken at a certain speed, not much more and certainly no less." ~ Catherine Norman
The faster you are going on cross country, the more you must generally think of maintaining a contact with your horse's mouth on the takeoff of a jump. No big crest releases!
Training a horse is sometimes like peeling an onion... As you make some progress in one area, the next area that you need to focus on often becomes clear.
Take your time when riding transitions. Many riders seem to rush through them just to get them done. Be conscious of preparing for each one, and feeling all of the details while you are making the transition - being ready to abort the transition if things start to go wrong.
When riders stiffen their shoulders it can cause them to also have tense, tight arms and hands. To relax your shoulders, take a deep breath in, and exhale fully... looking for the feeling that your shoulders and elbows drop and become supple.
The more contact you hold on your horse's mouth between jumps (and of course, on the flat as well), the more work you may have to do to half halt or stop. Try to be as light as possible, so that when you do ask for something, your horse will hear you.
"Our job is to prepare the line and canter, then ride forward to the jump. Riding forward to the jump is NOT accelerating to the jump. There is a difference. When riders get to a longer or shorter distance than ideal, the emphasis should be on the rider staying in the moment and conveying confidence to the horse." ~ William Fox Pitt
With horses, just like with people, let your actions speak for you. For example, you may think you are rewarding your horse when you say "Good boy" or "Good girl"... But if you do not also release the aid, your horse will not really feel rewarded for their effort.
When a rider does not have that classic straight line from their elbow to the bit, it is nearly impossible to have a quality contact. This is just one of the many reasons that having eyes on the ground is SO important. As many riders tend to ride with their hands either above or below that line, and have no idea that they are doing it. A good rein connection will elude you until you have found just the right alignment.
Always pay attention to how you finish every single exercise that you ride. Letting yourself or your horse fall into a heap as you pull up only creates bad habits for both of you. Always finish with a proper transition into the walk.
"The goal of training is to build the horse's mind and his muscles. Suppleness and relaxation require adequate muscle strength. Strengthening requires both contraction and relaxation. Blood flow and oxygenation occur when the muscle relaxes. If the muscle is kept in a constant state of contraction, it loses power and strength, and actually becomes smaller. Frequent rest periods, especially for a young horse at a free walk on a long rein, are necessary. The rest periods are not for a rider's fatigue, but to allow the horse to stretch and relax his muscles. The rest breaks will give you a completely new horse. This is the systematic gymnasticizing of the horse." ~ Klaus Balkenhol
Think of your leg, seat, and rein aids as the way you communicate with your horse. You don't physically push or pull him anywhere - you give him subtle signals. And if he doesn't initially respond to your subtle signals, you need to teach him to. EVERY horse can learn to respond to light cues, if taught properly.
The key to riding good "across the diagonal" movements in the Dressage ring is to ride deeply into the preceding corner, while keeping the impulsion through the turns, so that the energy level stays consistent throughout the movement.
If you truly do a good job of preparing for each transition that you ride, you will be able to give an aid that is as light as a whisper to execute it.
"Although breeders have created a better horse, the market has created a demand for a stronger, healthier, more powerful horse. It's easier to sell a horse that looks like a carefully developed eight year old, and not like a three or four year old just beginning his career." ~ Klaus Balkenhol
If your horse feels locked in the jaw and is bracing against you, you are probably bracing and pulling against him yourself. He will probably never let go unless you do.
"It is important that the neck is open at the throat latch. Too many horses too short in the neck in all disciplines. Today’s horses are always in a frame, but often they don’t seek the contact properly, and you can’t give high marks to a horse that is behind the bit." ~ Christoph Hess
If your horse is not "hot" to your leg, and you need a lot of leg to keep him going, how will he ever hear the leg aid that asks for something more... like a lateral movement or a flying change?
As we should always be striving to make sure that our horses enjoy their work, reward and incentives should be especially generous when we are asking for things that we know are currently difficult for our horses.
A horse doesn't become supple by trotting round and round the arena. So don't stay in the same pace or movement for too long! Lots of turns, circles, and transitions will be the most beneficial.
The horse should always be the one who sets the pace of the progression of both training and competition. Pushing too hard, too soon, will usually result in having to go back and start over.
Keep your thumbs closed on the top of your hand, AND keep those thumbs pointing forward! Do not let your hand position deviate so that your thumbs point toward each other, as this will create a block in your connection.
When riding a Dressage test, you should always be thinking about damage control… Within each movement, sometimes it is best to be happy with 90% of what you are capable of, rather than risking what you have to push for that final 10%. It definitely pays to know your horse well, so you know how much you can get away with asking for at any given moment.
"No complicated riding before the horses are going truly forward. In dressage, the difficulties are often created by a lack of good basic work (which is the foundation of the house)." ~ Nuno Oliveira
A horse must first be able to travel in a connected long and low frame before a proper higher head carriage can be achieved. If you struggle with lengthening your horse's neck while still maintaining a soft contact - be sure to master this connection before moving on to more advanced work. If you don't, all of your more advanced work will likely be incorrect and will lack the back connection necessary for true hind leg engagement.
"Most riders know the required movements, but not the directives, and that is what we judges pay attention to. We look to see how the horse is ridden in these required exercises. Is the horse ridden to the contact? Does he maintain rhythm and regularity in all gaits? Does he show a degree of suppleness appropriate for his level? Does the rider keep a tempo that facilitates balance? Even for a simple circle the directives are explicit: 'consistent bend around the rider’s inside leg, placement and control over the size of circle, reach to the bit and the quality of the gait.'" ~ Lilo Fore
As the old saying goes, "You are only as strong as your weakest link." If there is a hole in your basics, or your horse's basics… it will hold you back. You must go back to the foundation, to find and fix any weak areas before you will truly be able to progress.