There are many different patterns out there, but only two are appropriate for the hunters, as well as for ideal jumper turnout. The two options are the full body clip and the full body clip with a saddle patch.
In the full body clip, all of the hair is clipped from the body, legs and all or most of the head. How much of the legs and head you will have to clip will depend on how long your horse's natural coat is. If it is not excessively long, you should be able to clip the cheeks and under the jaw, blending the clip in with the natural hair where the cheek pieces of the bridle sit. If your horse has a very hairy face, you might need to carefully clip the entire face in order to prevent it from becoming drenched with sweat and to avoid an obvious clip line.
If your horse has very hairy legs, you will probably need to clip all of the way down each of the legs. If the legs are not excessively hairy, you might be able to blend the clip in with the natural hair somewhere along the forearm. As long as you don't end up with a blunt line, it should work. Your horse's colour will also play a part in determining how far you will need to clip. If the clipped colour is very different from the natural colour, you might not be able to blend the two together. Bays, especially the darker ones, are generally easy to blend because of their black stockings.
If your horse has any white legs, clipping them will make them much easier to clean and keep white!
Some riders like to leave a saddle patch of longer hair on the horse's back to provide extra protection. If you choose to leave a saddle patch, make sure that it is small enough to fit under your show saddle pad without any of the longer hair showing. The patch is generally only under the seat of the saddle, rather than extending down under the flaps where the horse is likely to sweat. Keep in mind that this patch of hair will be visible if you need to remove your tack to jog in front of the judge.
If you have never clipped a horse before and you plan on showing, it is a good idea to hire a professional to clip your horse. Clipping is learned hands-on and even the best of beginners is likely to leave some unsightly lines after a first attempt. If you would like to learn how to clip, it would be best to learn either in the winter when you will not be showing or on friends' horses that will not be showing. When you're in the show ring, you want the judge to be focused on your round rather than on the quality of your clip job. The clip should look as much like a natural summer coat as possible and clip lines look anything but natural!