LEAVE IT COMMAND
The leave it command is used to prevent your dog from picking things up on the ground that you don't want him to. This method will work with both puppies and elder dogs.
The first thing you need to do is to condition a marker that tells your dog that he is on the correct behavior that will get him a reward. While you are teaching this command you can either use your voice or a clicker. As clicker has a very distinct sound I would recommend using a clicker. So here are the steps for leave it command.
Step 1: Use clicker or your voice
Once you get your dog's attention click and then give him a treat and repeat this at least 15 times. The good way to tell wether your dog made the connection is if they turn to you right after they hear the click. In the early stage of the training encourage your dog to look at you. Eye contact is very important. If your dog happens to be too focused on your hand you can make a sound and click as he looks up at you.
Step 2: The goal of this step is to put treat in front of your dog and he will choose not to pick it up
Show him the treat in your hand and then close your fist. Allow your dog to sniff your fist and try to get it out. Your dog might be very eager to get the treat. He will start licking your fist and get excited. At this moment try to stay still and calm. The second your dog backs up click and reward (give him the treat). At this time it is important not to say anything to your dog because you want him to figure out on his own what he has to do to get that treat. Now you can start adding the command "leave it" as you close your fist. Eventually your dog will figure out what you want him to do.
Step 3: Put the treat on the floor and cover it with your hand
Cover the treat before your dog gets it. He will try to get it but again the second he backs up click and let him have the treat. After a number of consistent reputations when you give the "leave it" command your dog will be able to understand what is being said.
With leave it command you can prevent your dog from picking things up that might be dangerous for him. Find out what other Dog Commands will be helpfull.