One thing that I'd add that I haven't seen anyone mention yet, is you need to step back to the dog and give the reward while they're still in the "Stay", then give a release word, like "Okay". The key is giving the reward while they're still staying, not after the release or after say calling them to you, so that they'll think of "Stay" as a good thing. Also, use a happy voice to give the command, "Stay", like you would with "Come". I know I had a tendency to use a stern voice with that command, which makes it a dreaded thing for the dog, until my agility instructor pointed it out to me. Again, gotta make Stay a positive thing for the dog.

Par...