If you want to know what not to do - just ask - been there done that.
Before all the G Bears and now the wolves I packed in a camp and hunted for many years north of Yellowstone Nat. Park. You can not believe some of the strings that came by our camp. No doubt what a unprepared rookie and his stock looks like after a 20 mile pack trip. We won't mention what was seen when their horses or mules got around a gut pile for the first time, hobbled, or put on a high line etc. etc. for the first time.
A horse/mule/packing category would be a great addition and I am sure that a lot of information could be shared. The first bit of advise I always give when someone asks me what I look for in a horse or mule for the mountains. I always tell them I look for 3 things: attitude, attitude and attitude. If they are built right, have a decent attitude, I could care less if they were pink in color.