This is excellent advice from a top-notch competitor.
When you attend a horse show, not only watch the performances in the show rings, watch the warm up arena. As Frank Chapot says, you can get free lessons by watching the top riders in the warm up rings. Here at WEF, I love to watch how riders school their horses. I watch everyone and study the winners like Beezie, Mclain, Laura, Eric Lamaze, Doda, Nick Skelton, the list goes on and on. Watching position, distance, pace, turns, type of jumps they set (square, rampy, oxers, verticles). I check out their equipment, saddles, bits, tack, boots etc. Interesting to notice the type of horses they ride and how they ride them.
You can watch how the top hunter riders prepare their horses too. As well as watching the top equitation trainers, schooling their students before a class.
There is so much to be learned by observing. It is unbelievable free information, if you take the time to watch! If you have questions, ask your trainer or a fellow horseman.
When I was young, I glued myself to the warm up ring to watch the famous riders and their horses. It's wonderful to watch the rounds in the show ring. But there are sometimes even more valuable lessons to be learned in the warm up arena!