I had a hand in my big gelding's training -- he was born on my uncle's farm and he decided to use Dio as a way to teach me about imprinting and starting foals, and then when he was ready to be saddle broke (by that point he was mine), I had him sent to a trainer who was more than happy to "train" me at the same time, explaining everything he did, why, how, and then letting me try.
My two younger boys, Bandit and Dante, were both born to my mare, and I took all that knowledge from raising and training Dio to bring them both up to where they are now -- able to carry a saddle and rider at a walk (Due to their size, I wasn't overly concerned with saddle breaking), just putting the finishing touches on their cart training, and so quiet and well-mannered on the ground that a friend's 9-year-old sister shows them in halter classes with a moderate amount of success. I had another uncle that used to break/drive drafts, and he answered a few questions for me on that front, as well as referring back to Dio's training and a few other tips and tricks I've learned along the way.
Of course, I was lucky -- both boys have the personality of saints to begin with, and were very patient with me from day one.
I've also done some minor training with other's horses (breaking bad habits, ground work, stuff like that), and a few locals have discovered that I'm willing to hop on any horse and "ride the buck out"/work with them to accept a rider, though I don't train any but my own from start to finish. I just don't have the means or the facilities, haha. I do a lot of people-training, though!