Here are a few simple things I do to take care of my horses mane and tail. It makes her hair long and silky smooth.
-Every month or so I give her mane and tail a thorough washing with a horse shampoo designed to whiten (because her tail is white.) When I do this, I am careful not to scrub too harshly so that the hair is not damaged.
-Once the shampoo is washed out, I use a hair mask made for people. I discovered it because it works very well on my own hair, making it soft and shiny. It does the same for my horse.
(the brand I use is 'Nutrogena triple moisture; deep recovery hair mask.' It is a bit expensive, but it's consentrated so it lasts for a while. You could try similar off brand products, or even a suave conditioner if you need something cheep)
-With the hair mask on, I gently brush the hair with my fingers. Many people have advised not to brush hair when it is wet, because it is weaker and more easily broken. However, I find that if I am careful and only use my fingers, there is minimal damage to the hair.
By brushing it while the hair mask is in, it gives the product more time to work it's magic and it also makes it extremely easy to remove tangles.
When I finish I rinse it all out.
-Once the hair dries, I work a leave-in horse conditioner into the hair with my fingers. There are lots of products available, but I am partial to cowboy magic. I find that it smells good (unlike some horse hair conditioners) and it stays in the hair for a very long time. It also helps to prevent the hair from becoming tangled again, which I really like. Just don't use too much, because a little bit goes a long way.
This step is what really makes my horses mane and tail shine. It looks beautiful and healthy.
-For maintenance, I would recommend only brushing your horses mane and tail with your fingers. If a comb comes into contact with a small tangle it will break the hairs and leave you horse looking frizzy. But your fingers would feel the tangle so that you can stop and work it out.
I also reapply more conditioner when I feel the hair is becoming dry.
Feew! Sorry that took so long, I'm not sure what you already know. I hope this helps!