One of the most interesting aspects of photographing horses is that no two horses are exactly alike, in personality, conformation and appearance. This makes things interesting and challenging when working to take a good image of a horse. If you are photographing a horse without a human, you want to capture the expression and beauty of the horse. When you are shooting a particular breed of horse, learning about what the breed standards will help you.
Some breeds of horses have features that are easy to emphasize, and capture a good image – for example, Andalusians, especially stallions, will usually have a long flowing mane. One of the best ways to highlight the mane is either to get a photo of the horse as he is running, and the mane is flying up.
Arabians are prized for their long, elegant necks and dished faces, so emphasize those features.
Freisians have very large heads, and photographing them head on is not flattering, so when taking a portrait of a Friesian, I make sure that I use different angles so that his head looks noble, not huge.
Use your imagination when trying different angles.