Expression – The eyes and nose show the most emotion of the image, so make sure they’re in focus and try to include them, unless the image is a close-up. Ensure the horses ears are pricked forward, if they’re back the horse could appear bored or angry, throw something small into the air or make a noise to grab their attention if you need to, but be careful not to frighten them.
Action shots – Brighter lighting is often better for action shots as it means the legs and head won’t be blurred, it’ll also increase the quality (you may have to turn quality up manually). Take a lot of photos, the horses position often appears awkward and the more photos you take the more frequently you’ll get ones you like. Pre-focus the image and follow the horses actions rather than waiting for them to move into the shot.
Background – A plainer background will give the image better composition because it doesn’t distract attention from the horse or rider.
Angle – Low angle is often best for action shots and silhouettes. But with portraits keep the camera level with the eyes of the horse or rider, this will give them both a more flattering appearance.