not actually a lot of advice, but remember to BREATHE. Inhale, exhale. Deep breaths. Even hum a little song in your head to relax you. i find it helps for me, lots of times when i think my horse is about to do something dumb ill stop breathing and tense up, he feels it, and reacts to it. If i just concentrate on my breathing, we're fine. After a few solid rides, im able to relax no problem.