To teach your dog to leave something you don’t want them to get hold of, start with a tasty treat in one hand and a boring ‘leave it’ item in the other. Hold the hand with the item out, let them sniff and wait for them to look or move away from it. When they do, mark this and reward them with the tasty treat from the other hand. Repeat this until your dog is reliably looking away, and then start to add in the cue. Say “leave”, hold out the ‘leave it’ item out, then as you pooch looks away, mark and reward them. Over time your dog will start to look away as soon as they hear the cue. Try it in new places and add in distractions. You can also begin to add in some movement by placing the ‘leave it’ item on the floor, and then dropping it from a low height. If at any point your dog is struggling to leave it, go back to a stage where they were successful and progress more slowly.
Before introducing the 'leave it' command, fair trade can help teach your puppy to give you something back because they will receive something better in return. You can use fair trade by picking a toy for your dog to play with, making sure it isn't their favourite so that they are more likely to release it. Encourage your dog to play with the toy for a few seconds, then place a handful of super tasty treats on the floor next to them, and let them make the choice to move from the toy to the food on their own. Once they have finished their treat, let them play with the toy again, and repeat this a few times, making it a fun game that your dog enjoys. Once your pup is letting go of the toy for the food you can start introducing your fair trade cue, saying it when your pup has hold of the toy, and placing a handful of tasty treats to the side.