Liz Norris, thanx)
It's a good decision!)
I'd give you a couple advices:
1) One of rules i use - more water, less colors. At first, because you can make more mistakes and then fix them, and also this rule allows you to chose color you need more correctly. Dark and intensive colors i use only for making details, such as nostrils, eyes, mane, some shadows. But don't forget to dry watercolor layers, before painting another (in case you doesn't want to mix colors of course))
2) yes, you're exactly right. At first i put light colors, then with each step put more and more intensive. But try to do this very carefully. This allows me to make an object with more volume.
3) Try to use more colors. it makes artwork with more volume and looks better) Don't avoid using cold colors (blue and green tones) when you're painting a chestnut and bay horses. And on the contrary use a warm colors when you're painting a black or grey horse for example.
These are the main things i always try to follow

I'll be glad to see your watercolor paintings.
P.S. Sorry for mistakes, it's not my first language)) I hope you will understand what i meant. :lol: