I like Clinton Anderson and I actually started my horse, using his old video, "Starting Colts Under Saddle." This was the first horse I'd ever started and I was in my early 50s! I got as far as having my husband pony me around an indoor arena and then I took Smokey to a trainer who told me she was very impressed with the results. Clinton is popular for a reason and he even has a DVD for gaited horses. Check his website. I also like Parelli and he has a slightly different approach. Parelli is into figuring out "horsenalities" (which is fun) and using that as part of his training program. He is more cerebral and slow, but you can become a member for around $10/month and get loads of good information, which includes online videos, files you can download and a pretty good forum group.
I've also started doing clicker training and I LOVE it. It's a great way of reinforcing what you are already doing or helping with problems you might be running into. For instance I made huge improvements with my mare that does not like to load onto a trailer. In fact, I had trouble keeping her off of it using the clicker.
Winter is coming so my horse activities slow down, but this is something I can work on in their stalls or the barn isle. You are only limited by your imagination and there are plenty of websites, books and DVDs available. Check out Amazon for books (and great reviews). The one I like the most is "Getting to Yes."
I think it's great that you want to learn more. Good for you!