1. Start with a bath the day before the session. It's up to you on what you use on your horses body/mane but I highly recommend using something similar to "Mane n' Tail Ultimate Gloss". The products you use on your horse(s) will have their coat pop and have that natural shine in the final image. After you have bathed your horse keep a cooler and or sheet on them till the day of the session to keep them free of any dirt.
2. If you are going to be braiding/banding your horse you should try to do so the day of the session or the evening before to have the bands/braids look just as new. Don't be afraid to get creative and use different color bands or string when braiding!
3. The day of the session, this is when you should be giving your horse a good grooming to have any remaining dirt removed. Add a very small amount of baby oil to your horses nose, neck, and eyes to make them shiny and to define their muscles. (You can even add a small amount to their mane and tail for extra shine!)