I attended a clinic by Ed and Martha Wright years ago that was just awesome. If you have a chance to go, I highly recommend that you do. They covered horsemanship, tack, and gave one-on-one instruction. I learned as much from watching them instruct others as I did from the instruction they gave me. I also learned a lot from the other attendees. I loved the stuff they taught about how different bits work on the horse. I liked their clinic so much, that when I was their book a few minutes ago, I just had to order it.
I read Barrel Racing (the Western Horseman book) by Sharon Camarillo when I first started out, and I still refer back to that sometimes. Camarillo makes the information she presents accessible (I read it when I was a freshman in high school and had no trouble with the concepts) and easy to implement.
If you've seen/read/attended something that was good (or bad), let us know. I'm always looking for ways to do better with my horses, and I'm sure you are too.