When it comes to dressing yourself up for the hunter ring, conservative is only the way to go. You want the horse to stand out, not the rider. The Equine Canada rule for rider attire is the following:
ARTICLE G109 DRESS
2. Competitors should be neatly and suitably dressed in coat, shirt and tie, choker or stock, breeches or jodhpurs and boots. Black or brown smooth leather half chaps are permissible providing they match the boot colour.
... Only approved helmets (see Article G102) of a conservative color are allowed.
3. If competitors are not suitably dressed, the judge may refuse to allow them to compete.
4. In hunter competitions, in extremely hot weather, coats are optional at the discretion of the Competition Committee.
6. At all EC-sanctioned competitions, anyone mounted on a horse must wear the required headgear (see Article G102.1) as well as safe, appropriate footwear.
So what does all of that mean?
You will need an ASTM approved helmet of a conservative colour. That means no bright colours and no bling. Ideally, your helmet will complement the rest of your outfit and not really stand out at all. There are many different styles out there and some are much more conservative than others. When in doubt, providing it fits you well, choose a more conservative helmet over a flashier one.
If you have long hair, it should be contained in a hairnet. The "show bow"-type hairnets that have a pocket for your hair and sit at the base of your neck are not really acceptable for the hunter ring. The best way to contain your hair is to put your hair into a low ponytail, flip it up over the back of your head, cover everything with a traditional hairnet that matches your hair colour and then put your helmet on to hold it all together. This method keeps your hair up and out of the way while looking very neat. The most popular way of tying long hair in the hunter ring is to have the hair cover the tops of the rider's ears.
If worn, make-up should be applied sparingly. Remember, the emphasis should be on your horse. The same goes for any jewelery that you might wear; less is more.
Opt for a show shirt with long sleeves as the lack of a cuff on short-sleeved or sleeveless shirts can give you an unfinished look. You can choose whatever colour you want for your shirt but make sure that it doesn't clash with your jacket. The most common colours are white and pastels. When you want a very formal look, go with a white shirt.
Your show shirt will come with one or two chokers that are to be fastened over the collar. Once you have buttoned up your shirt, fasten one of the chokers securely over your collar to finish the look.
There are several different materials to choose from depending on your budget and personal preferences. There are lightweight, machine-washable or waterproof styles available. The newer "soft shell" jackets can sometimes lack the formality desired for the hunter ring, especially when combined with metallic buttons and over-styled pockets/lapels.
For a hunter classic or stake class, a shadbelly (seen in the photo on the right) is appropriate but not mandatory. If you choose to wear a shadbelly, you will need to use a stock tie over your show shirt. Shadbellies are too formal of a choice for regular hunter classes.
Your number, which is provided to you by the horse show, should be tied around your waist using a string that matches your jacket. String it through the holes such that the string passes behind the number, not in front of it (potentially obscuring the number). The number should be centered on your back unless the judge asks for it to be moved to one side or the other.
Breeches should be light in colour. Beige (or greenish beige) is appropriate for all showing in the hunter ring. White breeches are occasionally worn in hunter classics or derbies by men but beige breeches suit the hunter ring much better for women and for most men's classes.
Hunter riders should wear field boots. These are the boots with laces in front, as shown in this photo. There is no way to go wrong with black leather. Be sure to polish your boots to a shine before you show.
Leather half chaps worn with matching paddock boots are allowed but field boots are the better choice.
Spurs may be worn but they are not mandatory. Spur straps should be clean and match your boots.
Gloves are not mandatory, either, but they do look good. Black gloves are ideal, but brown gloves can be appropriate if they match the rest of your outfit. White gloves are never appropriate in the hunter ring since the rider is not meant to stand out.