The more I work with very young puppies, the better I understand the power of the most fundamental trained behavior: Sit.
Working with a breeder, we started training pups at seven weeks. Day 1 of training meant introduction to leash and collar, lure-reward training, and sitting on cue. One of the goals: create dogs whose default behavior under any circumstances is Sit. What does that mean? It means that rather than jumping on people for attention, a pup will run up to a person and Sit. It means the pup is learning self-control and an implied Stay which can become a trained Stay. And it means pups are learning to love to learn.
Whether your dog is three months or three years, Karen Overall sums it up best in her book, Clinical Behavioral Medicine for Small Animals:
For a dog that already knows how to sit, the only problem is going to be to reinforce this for everything that the dog wants. The rule is: the dog must sit and be quiet to earn anything and everything for the rest of its life. This includes sitting for the following:
If you train your dog to do two things well - sit for everything and walk politely on a leash - life with Fido will be good.Food and feeding
Being able to go out and come in
Having the leash, halter or harness put on
Having feet toweled
Being invited onto the bed or sofa (if desired)
Playing with toys
Having a tick removed
Having a wound checked
Anything the dog wants