I normally talk to my horse but I mostly tell my self that I'm training with a whole lot of other people. I sometimes can't get to sleep the night before a show so I usually imagine the I'm riding my dream horse on the beach ( or where ever you want to be). I know it sounds crazy but it works for me!
I use handsanatisers I know crazy right but there are ones at Bath and Body works that are made to help with stress relife and to help make you relax I use them at every show or big events they have saved me many times
my friends have these gummies that they get at a health good store and they come in a tin which makes you feel relaxed, they also say it makes you feel warm and fuzzy which they find helps they're stress levels!!
Breathe- I know it sounds cliche, but you can't relax if you're not breathing. Just take a couple deep breaths, and give yourself a small, reasonable, achieveable goal (for my horse and I, frequently that's staying calm with other horses in the arena). Then just do your best to accomplish that goal, and try not to worry about anything else. Oh, and make sure you eat and stay hydrated! Being hungry never helps with stress and anxiety. (Hope I'm making sense, I just woke up).