I find with mules it is easier "to ask" instead of "tell." If you try and force them they get quite opinionated....but if you make a suggestion lightly they are much more inclined to say "why not" and do what you want. Food is great or any way that you can get their curiousity up about what you are doing.

Horses are the same except they can be intimidated into doing stuff easier. I don't like to use that feature about horses as prey animals, and I work consistently at being as light as I can with my horses and they offer me much more. I really don't need reins to ride anymore as a result. And just yesterday my horse was standing 10 ft away from me and I climbed on a fence and called her to me and she sidepassed over to me at the fence and got herself in just the right into position for me to hop on. My friends were pretty blown away...:)