If you are new to equitation, don't just look at what other riders are riding on.... look at their whole picture. Equitation is how the rider rides. Are your riding skills not as polished as those who are winning... that is what is being judged. Total picture - the rider is sitting well in the saddle, straight, tall, relaxed. Their aids (use of legs, hands, spurs - if worn, or crop- if used like in an over fences class are correctly applied and done with care for horse, not severe or mistimed) The rider is dressed in clean, well fitted clothes (and they don't have to be the most expensive, or showiest) 4-H is especially noted for allowing simple garb for both western or english. You do the BEST with what you have... that means perhaps making sure your showshirt is clean and pressed, jeans ironed and of the right length. Boots POLISHED, and well buffed before entering the ring. (Even if you have no groom, you can use a rag to wipe off your dusty boots to give a last minute gloss to their finish) The horse: the horse is CLEAN, well groomed, in good condition. The feet are clean and well trimmed. The mane and tail well groomed with proper attention to best appearance for your breed or type of showing. English, it's always nice to see even schooling show riders who braid their hunter horses. It shows respect for yourself and the judge who's made the effort to come to judge you. Your tack is CLEAN, oiled and well fitted to your horse. Saddle fits YOU and the horse. Little children in adults saddles is not a correct picture - you have to have a well fitted saddle to be best seated to be able to ride correctly.
Bridle fits horse properly, bit sits correctly in the mouth, neither too low or too tight. Headstall is set so that it is level, (nothing worse than watching a rider go round an entire class with a browband nearly blinding his horse, and the other side up to his ear... DETAILS, that make the total picture perfect!) Reins - no twisted reins, rein contact even and reins held steady and correctly.
The ride: the horse is obedient to the aids of the rider. The rider presents the horse in a good working frame with proper cadence of stride, relaxed and correct in all gaits. If english the working trot is ridden posting on correct diagonals, and the sitting trot is not a slowed down trot, you merely sit the working gait as required. The canter is a forward moving gait with the horse in self carriage not on the forehand. (Too often beginning equitation riders are not aware of how their horse is really moving, so working with a trainer or coach who can help you learn the best presentation of your horse is the way to achieve success.) Watch videos of the equitation type you want to succeed at. There are tons of great equitation videos out there on the internet... English, watch the Maclay Medals- Western there are AQHA, Arabian, and Paint videos you can watch.
Saddle color is preference of the rider - From 30 - 50 Ft away where the judge is in the arena, the color of saddle is of little consequence. What affects their scoring of your ride is your position in that saddle, and your use of seat legs and hands. Your attitude of riding - are you rigid, sloppy, leaning, crooked... Hands and arm movement, or lack of giving to the horse, bouncing hands, cocked wrists, all are easily seen by judges.
Tests: if your equitation class has a test, you execute the test to the best of your ability using the arena to best advantage. You ride accurate to markers or focus on center of jumps, etc... Planning the entire course of the test, and breaking down each segment so you ride each piece correctly... Practice, Practice, Practice
Schooling shows are a great tool to learn how to do things better, if the judge provides feedback to the riders. If you video your lessons and your show rides, you can also evaluate and have your coach evaluate with you what is happening and where you are making errors. Ask show manager if you may ask the judge about your ride - after they are done judging. You should always have the ring steward or manager arrange for this. Many judges will talk to school riders in the final line - up after the placement of the class.
A last thought - if things don't go perfectly in an equitation class, such as your horse doesnt get the correct lead right off... it is HOW you the rider attempt to correct the mistake that a judge will watch. Yes, you errored in the initial asking, but, do you notice right away or go 3/4 round the ring until somebody on the rail says "you're on the wrong lead" Learning to deal with the mistakes quickly, quietly and subtlely is the sign of a rider who is attempting to improve their abilities. Thinking in the saddle, You are the driver, the one in control, not just a passenger and that is what is being judged. Learning to ask the horse to do things correctly and look good doing it. As a judge I've many times placed a horse and rider of less than stellar appearance over the 'brand new' shiny outfit, when that first team are the more competent and capable correct team. Workmanlike appearance when clean and well cared for is perfectly acceptable, and preferable to the rider who has all the fancy gear but doesnt know their seat from a bump on a log. Happy riding, Keep it fun, Keep it safe and Keep learning!