Words won’t mean much to your new puppy or your untrained rescue dog until he learns how to learn, until he makes the connection between the meaningless sound you are making and the action for which it stands. Once he gets one connection, the others will begin to come more quickly, particularly if you always use the same word to mean the same thing, particularly if you are clear. But until he makes that first connection, it’s all background noise.
The easiest first word/action is often SIT. Sit is easy to teach and pretty easy for a pup to learn. Take a favorite toy, hold over the dog’s head, say “Sit.” In order to see the toy dangling over his head, a puppy will look up, lose his balance and sit. Say “Good dog,” give him the toy, try it again later. But what if your dog is an older dog, or an older puppy, a puppy who can stand on his hind legs easily, and will in order to get the toy. What if you can’t even get eye contact, let alone ear contact? Then you try something else.
Most dogs of any age love to follow their person. So begin this useful game off leash if that works or on leash if that’s what you need to do. And after the pup is hooked, after his tail wags and wags as he follows you, add a word or two. “Let’s go,” or “Follow me” or whatever suits your fancy. This might lead you to the sit and eventually to higher education.
But what if it doesn’t?
You can try “Take it,” using a small, squeaky toy. Hold out the toy, say “Take it,” give the toy to your dog. And if this works, once your dog knows “Take it.” you can add “Wait.” After a week of the first, add the second. Hold the toy in one hand, hold up your pointer on the other hand and tell him “Wait.” If he hesitates for a moment, tell him “Tale it” and add some verbal praise. After a few weeks of Follow Me, Take it and Wait, your dog should be ready for Sit, a word/action duo that, even for just a moment at first, will give him that moment to think about vocabulary and the fact that the sounds you make, at least some of them, are more significant than he previously believed.
Words, words, words. Your dog can and should learn many of them. The trick is starting off on the right foot. And then how far you go is up to you.