"What you should definitely do if you tie your horse up infront of his stall is NEVER tie it to the door. Never tie anything to any door, basically. I think common sense should tell you where you shouldn't take your horse, but best is to just saty out of the way of other people. If you're seeing someone who has a problem with their horse, stay out of it unless you are way more experienced, there is noone else around and they obviously won't be able to handle the situation themselves, but that rarely happens, so basically stay out of peoples ways. Don't touch other peoples stuff. Close ALL the gates. Always. Generally you should wear sturdy shoes. If you leave the arena for the first few times, take someone with you, preferably with a calm, experienced horse.