Hey BSMS, I won't be that much use in where you can get your hoof trimming education as I live on another continent, but I wanted to encourage you. Three years ago my husband and I moved out into the sticks to our own place and no reputable farrier travelled that far! The people that did come didn't trim hooves correctly and charged an arm and a leg. So I decided to trim my own.
In one way my advantage was that my father had been through this and ended up trimming and shoeing himself. He learnt by observing qualified farriers and by specialist videos on corrective trimming and shoeing, and got so good people brought their racehorses to him to sort out gait problems. So I grew up with basic instructions on how to trim my own horse, and opportunity for feedback, and lots of exposure to the theory and practice of horse trimming. It's physically demanding though, especially when you have hot summers which turn hooves into hardwood, so it was nice to have an experienced family member you could trade another job, like mucking out, for this one.
Twenty years later, I decided to trim again. The problem: I have an old back injury, and I'm really tall, and I have arthritis in my finger joints, so I'd rather someone else competent did it, but that was not on offer. If you are short, and have short legs, rejoice: This will make trimming much more comfortable for you and the horse. You won't be bending your back as much. Anyhow, the best tips I ever got for making the job physically easier is to make sure you invest in really good tools that don't blunt quickly and are comfortable to use in your hands. I've used both good and bad hoof nippers, and it's a world of difference. Ditto rasps. Good leather gloves and at least wearing thick denim and long sleeves will reduce injuries to yourself as you become competent.
If you have a dry summer, trim the same day it rains no matter if they can wait a few weeks or not. The hooves are so much softer then. Some people stand their horses in a pond or go to the beach to splash before trimming.
Trim often - it makes things easier. Every 4-6 weeks. I'm sure you can find a mentor in your area, nothing beats a good mentor; or even ask a farrier if you can spend the odd day on the job with them, and observe and ask questions. There are very good DVDs and books out there; I'm sure others will point them out.
Like you I have three horses, and I'm now coping. I also do our three donkeys, who are way easier to trim! Good luck with it all. You'll get there!