How to Band a Mane
To band your horse's mane, start by trimming it to about 6 inches long and combing some hair gel through it. Then, starting at the end of the bridle path, part a section of hair that's as large as the tooth of a comb, and wrap an elastic band around it 3-4 times. Next, secure the band, and lay the hairs flat before repeating the process with the next section of hair. Finally, work your way down the mane, and then band your horse's forelock.
Pick up the necessary supplies. To start, you'll need a selection of 50-100 elastic bands in a color that compliments your horse's mane; you can choose to use a matching hair color, white bands for a black mane, or black bands for a white mane. You will also need a pulling brush for thinning the mane, a banding comb, a hair clip or two, and some sort of product to get the mane sticky. Quick Braid is a great product, but cheap hair gel will work in a pinch. You may also need a step stool depending on the height of your horse, or your own height. Organize your tools in an easy to reach place. Do a preliminary trim. If you've never banded your horse's hair before or it has grown out quite a bit since your last attempt, it will be easiest to cut off most of the mane before you start the process. Use your scissors to cut the mane to be about six inches long - it doesn't have to be perfect or even. You'll do a second trim when you finish banding to remove any remaining length and to even it out. Prepare the mane for banding. Brush through the mane with your comb to remove any tangles or knots. You can dampen it with a bit of water to make this easier. If your horse's mane is very thick, using a pulling brush to thin it out at this point. Apply your Quick Braid or gel until the hair feels workable, but not too sticky. Comb the product through the mane so it is applied evenly. You don't have to thin your horse's mane unless it is particularly thick. Section out your first band. Start at the end of the bridle path, and part out your first section of mane. Using your banding comb, for a pro mane, use only a section as large as a tooth of the comb. For a quicker mane, make it the width of two teeth. Use your hair clip to hold the remaining hair out of your way. Band the first piece of hair. Take a single band and wrap it neatly about the selected section 3-4 times or until the band is snug. The band should be level with the edge of the horse's crest so that the bands will echo the shape of the crest as you work along the mane. Secure the band and lay the hairs flat. Reach under the band and take a small section of hairs and part it in two. Using both hands, take one piece in each and pull the pieces gently - slightly downward and to each side. It should look like you are making an upside down "V" under the band. Pull gently on these pieces upward along the neck, toward the crest, until the band pulls snug against the horse's neck. Create a second band. Move onto a second section of hair, following all of the aforementioned steps for dividing, banding, and securing the band. Try to line up the band so that it is even with the first one, giving the most clean and sleek appearance. Finish banding. Work down the neck following the pattern of banding you've created with the first two. Make sure that all of the sections of hair are of an even thickness, and that all the bands line up together. You may need to re-wet the mane regularly as you work. Do a finishing trim of the mane. Depending on personal preference and the class you are performing in, you may have a specific mane length in mind. Typically though, the mane is cut to be 2–4 inches (5.1–10.2 cm) long total. Start at the first band near the bridle path, and cut the man off in a clean line with the scissors. Work down the mane cutting each individual band, making sure that they are all even lengths. Band your horse's forelock. Wet it down as you did the mane and apply product. Use the banding comb to help you separate the forelock into three sections. Braid the forelock down about an inch and then band it up right where the hair from the bottom of the forelock grows. Tighten down the band just as you did the mane. Finish up the mane. Spray or sponge on some Show Sheen (or a similar product) when you are finished to add gloss and shine to your completed mane and forelock. Be careful not to apply it too thickly though, as this may counteract your attempts to appear sophisticated and leave it looking greasy. 
Pick up the necessary supplies. Do a preliminary trim. Prepare the mane for banding. Section out your first band. Band the first piece of hair. Secure the band and lay the hairs flat. Create a second band. Finish banding. Do a finishing trim of the mane. Band your horse's forelock. Finish up the mane. 