http://www.dogforums.com/3-dog-training-forum/46997-can-someone-tell-me.htmlI think the most common mistake in training "stay" is asking too much, too early. There are a few criteria when it comes to a good "stay" -- in other words, a few things that you're asking your dog for: duration (a long stay), distance (a stay from afar) and distraction level (a stay in the dog park as opposed to a stay in your backyard). Train only ONE criteria at a time, and when you start out training "stay" for the first time, all three criteria should be as low as possible.
That means you put the dog in a sit right in front of you, in a low-distraction environment, and expect the butt to stay on the ground for all of maybe one second. If the dog tries to get up, you can either use a no reward marker or say "ah ah"; stick your hands out in a stop sign and put the dog back into a sit. Remember, you only want ONE second of sitting, not more. If the dog can do this one second, praise and treat. Don't add a "stay" cue yet.
As your dog masters the 1-second stay, right in front of you, you can start increasing the criteria. For example, you may ask for a 3-second stay right in front of you. But remember, when you want to start tightening one criteria, all the others must go back to zero (or as low as possible). For example, you want to work on distance -- then you go back to 1-second stays, 2 metres away from you, in a low-distraction environment. Or if you want to work on distraction level, you go back to 1-second stays, right in front of you, in a higher-distraction environment.