Definitely the most important thing I learned is that if you do good for them, they'll do good for you. To explain- I worked at a racehorse stable, after years of wanting a job with horses, and being obsessed with them for as long as I can remember. To me, horses are amazing, graceful, beautiful animals. To the people I worked with, horses were a way of making money. I was new to the industry and of course given the horses to groom that no one else wanted. They were horses that came from unknown family lines, and horses that no one thought would get anywhere. Everyone else had the horses bred from all the big winners, , great bloodlines, and moneymakers.
Everyday, I went in early to say goodmorning to my horses, and all day I was very gentle with them, and always smothered them with hugs, kisses, and love. I considered myself their mother, and they were my fur kids. The other people I worked with would yell and scream at their horses if they were bad. They cared about their health to make them money, but didn't really care about the horses themselves.
After working there for almost 2 years, I had one 'unwanted' mare make almost 200,000, I had a filly come in 4th in all of ontario for 2-year-old pacers, and a few others horses do things that were never expected of them.
Turns out, I later found out that the 2-year-old filly that came in 4th in the province, had mush for knees. She had serious knee problems, and the doctors that examined her said that it's a congenital condition she was born with. They said they were surprised she could jog, let alone race. To this day I truly believe that she was able to race because I treated her with so much love, that she wanted to do good for me.
I feel that way about all the horses I was caring for. People that had horses with the good bloodlines, didn't get anywhere with them, and I had the 'bad' horses, and they did great things. It's all in the way you treat them. If they are loved, and happy, they will do their best at what you ask of them. They will be happier in general, and it will show in all the things they do.